diff --git a/.travis.yml b/.travis.yml
index 305fad1e4a7..50ff61e20f4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,7 +5,8 @@ node_js:
 
 sudo: false
 
-before_script: npm install -g codeclimate-test-reporter
+before_script: 
+  - npm install -g codeclimate-test-reporter
 
 after_script:
   - cat coverage/lcov.info | codeclimate
diff --git a/Jakefile b/Jakefile
index 324356a4af5..4c971efe0c9 100644
--- a/Jakefile
+++ b/Jakefile
@@ -3,7 +3,6 @@
 var fs = require("fs");
 var os = require("os");
 var path = require("path");
-var child_process = require("child_process");
 
 // Variables
 var compilerDirectory = "src/compiler/";
@@ -26,7 +25,8 @@ var thirdParty = "ThirdPartyNoticeText.txt";
 var nodeModulesPathPrefix = path.resolve("./node_modules/.bin/") + path.delimiter;
 if (process.env.path !== undefined) {
    process.env.path = nodeModulesPathPrefix + process.env.path;
-} else if (process.env.PATH !== undefined) {
+} 
+else if (process.env.PATH !== undefined) {
    process.env.PATH = nodeModulesPathPrefix + process.env.PATH;
 }
 
@@ -203,7 +203,8 @@ function concatenateFiles(destinationFile, sourceFiles) {
 var useDebugMode = true;
 var host = (process.env.host || process.env.TYPESCRIPT_HOST || "node");
 var compilerFilename = "tsc.js";
-/* Compiles a file from a list of sources
+
+   /* Compiles a file from a list of sources
     * @param outFile: the target file name
     * @param sources: an array of the names of the source files
     * @param prereqs: prerequisite tasks to compiling the file
@@ -214,8 +215,9 @@ var compilerFilename = "tsc.js";
     * @param outDir: true to compile using --outDir
     * @param keepComments: false to compile using --removeComments
     * @param callback: a function to execute after the compilation process ends
+    * @async
     */
-function compileFile(outFile, sources, prereqs, prefixes, useBuiltCompiler, noOutFile, generateDeclarations, outDir, preserveConstEnums, keepComments, noResolve, stripInternal, callback) {
+    function compileFile(outFile, sources, prereqs, prefixes, useBuiltCompiler, noOutFile, generateDeclarations, outDir, preserveConstEnums, keepComments, noResolve, stripInternal, callback) {
     file(outFile, prereqs, function() {
         var dir = useBuiltCompiler ? builtLocalDirectory : LKGDirectory;
         var options = "--module commonjs -noImplicitAny";
@@ -254,17 +256,9 @@ function compileFile(outFile, sources, prereqs, prefixes, useBuiltCompiler, noOu
 
         var cmd = host + " " + dir + compilerFilename + " " + options + " ";
         cmd = cmd + sources.join(" ");
-        console.log(cmd + "\n");
 
-        var ex = jake.createExec([cmd]);
-        // Add listeners for output and error
-        ex.addListener("stdout", function(output) {
-            process.stdout.write(output);
-        });
-        ex.addListener("stderr", function(error) {
-            process.stderr.write(error);
-        });
-        ex.addListener("cmdEnd", function() {
+        exec(cmd, function() {
+            console.log("")
             if (!useDebugMode && prefixes && fs.existsSync(outFile)) {
                 for (var i in prefixes) {
                     prependFile(prefixes[i], outFile);
@@ -274,14 +268,14 @@ function compileFile(outFile, sources, prereqs, prefixes, useBuiltCompiler, noOu
             if (callback) {
                 callback();
             }
-
-            complete();
-        });
-        ex.addListener("error", function() {
+            else {
+                complete();
+            }
+        }, /* errorHandler */ function() {
             fs.unlinkSync(outFile);
             fail("Compilation of " + outFile + " unsuccessful");
         });
-        ex.run();
+
     }, {async: true});
 }
 
@@ -324,19 +318,8 @@ compileFile(processDiagnosticMessagesJs,
 // The generated diagnostics map; built for the compiler and for the 'generate-diagnostics' task
 file(diagnosticInfoMapTs, [processDiagnosticMessagesJs, diagnosticMessagesJson], function () {
     var cmd = "node " + processDiagnosticMessagesJs + " "  + diagnosticMessagesJson;
-    console.log(cmd);
-    var ex = jake.createExec([cmd]);
-    // Add listeners for output and error
-    ex.addListener("stdout", function(output) {
-        process.stdout.write(output);
-    });
-    ex.addListener("stderr", function(error) {
-        process.stderr.write(error);
-    });
-    ex.addListener("cmdEnd", function() {
-        complete();
-    });
-    ex.run();
+
+    exec(cmd);
 }, {async: true})
 
 desc("Generates a diagnostic file in TypeScript based on an input JSON file");
@@ -401,6 +384,7 @@ compileFile(nodeDefinitionsFile, servicesSources,[builtLocalDirectory, copyright
 
                 // Delete the temp dir
                 jake.rmRf(tempDirPath, {silent: true});
+                complete();
            });
 
 var serverFile = path.join(builtLocalDirectory, "tsserver.js");
@@ -449,10 +433,8 @@ compileFile(word2mdJs,
 file(specMd, [word2mdJs, specWord], function () {
     var specWordFullPath = path.resolve(specWord);
     var cmd = "cscript //nologo " + word2mdJs + ' "' + specWordFullPath + '" ' + specMd;
-    console.log(cmd);
-    child_process.exec(cmd, function () {
-        complete();
-    });
+
+    exec(cmd);
 }, {async: true})
 
 
@@ -503,22 +485,24 @@ var refTest262Baseline = path.join(internalTests, "baselines/test262/reference")
 desc("Builds the test infrastructure using the built compiler");
 task("tests", ["local", run].concat(libraryTargets));
 
-function exec(cmd, completeHandler) {
-    var ex = jake.createExec([cmd], {windowsVerbatimArguments: true});
-    // Add listeners for output and error
-    ex.addListener("stdout", function(output) {
-        process.stdout.write(output);
-    });
-    ex.addListener("stderr", function(error) {
-        process.stderr.write(error);
-    });
+/* Executes a command
+ * @param cmd: command to execute
+ * @param completeHandler?: a function to execute after the command ends
+ * @param errorHandler?: a function to execute if an error occurs
+ * @async
+ */
+function exec(cmd, completeHandler, errorHandler) {
+    console.log(cmd);
+    var ex = jake.createExec([cmd], {windowsVerbatimArguments: true, interactive: true});
     ex.addListener("cmdEnd", function() {
         if (completeHandler) {
             completeHandler();
         }
-        complete();
+        else {
+            complete();
+        }
     });
-    ex.addListener("error", function(e, status) {
+    ex.addListener("error", errorHandler || function(e, status) {
         fail("Process exited with code " + status);
     })
 
@@ -537,7 +521,7 @@ function cleanTestDirs() {
     }
 
     jake.mkdirP(localRwcBaseline);
-	jake.mkdirP(localTest262Baseline);
+    jake.mkdirP(localTest262Baseline);
     jake.mkdirP(localBaseline);
 }
 
@@ -548,10 +532,14 @@ function writeTestConfigFile(tests, testConfigFile) {
     fs.writeFileSync('test.config', testConfigContents);
 }
 
+/* Removes project output
+ * @async
+ */
 function deleteTemporaryProjectOutput() {
     if (fs.existsSync(path.join(localBaseline, "projectOutput/"))) {
         jake.rmRf(path.join(localBaseline, "projectOutput/"));
     }
+    complete();
 }
 
 var testTimeout = 20000;
@@ -580,14 +568,14 @@ task("runtests", ["tests", builtLocalDirectory], function() {
     // timeout normally isn't necessary but Travis-CI has been timing out on compiler baselines occasionally
     // default timeout is 2sec which really should be enough, but maybe we just need a small amount longer
     var cmd = host + " -R " + reporter + tests + colors + ' -t ' + testTimeout + ' ' + run;
-    console.log(cmd);
+
     exec(cmd, deleteTemporaryProjectOutput);
 }, {async: true});
 
 desc("Generates code coverage data via instanbul")
 task("generate-code-coverage", ["tests", builtLocalDirectory], function () {
     var cmd = 'istanbul cover node_modules/mocha/bin/_mocha -- -R min -t ' + testTimeout + ' ' + run;
-    console.log(cmd);
+
     exec(cmd);
 }, { async: true });
 
@@ -619,7 +607,6 @@ task("runtests-browser", ["tests", "browserify", builtLocalDirectory], function(
 
     tests = tests ? tests : '';
     var cmd = host + " tests/webTestServer.js " + port + " " + browser + " " + tests
-    console.log(cmd);
     exec(cmd);
 }, {async: true});
 
@@ -635,14 +622,12 @@ function getDiffTool() {
 desc("Diffs the compiler baselines using the diff tool specified by the 'DIFF' environment variable");
 task('diff', function () {
     var cmd = '"' +  getDiffTool()  + '" ' + refBaseline + ' ' + localBaseline;
-    console.log(cmd)
     exec(cmd);
 }, {async: true});
 
 desc("Diffs the RWC baselines using the diff tool specified by the 'DIFF' environment variable");
 task('diff-rwc', function () {
     var cmd = '"' +  getDiffTool()  + '" ' + refRwcBaseline + ' ' + localRwcBaseline;
-    console.log(cmd)
     exec(cmd);
 }, {async: true});
 
@@ -689,13 +674,6 @@ task("webhost", [webhostJsPath], function() {
     jake.cpR(path.join(builtLocalDirectory, "lib.d.ts"), "tests/webhost/", {silent: true});
 });
 
-// Perf compiler
-var perftscPath = "tests/perftsc.ts";
-var perftscJsPath = "built/local/perftsc.js";
-compileFile(perftscJsPath, [perftscPath], [tscFile, perftscPath, "tests/perfsys.ts"].concat(libraryTargets), [], /*useBuiltCompiler*/ true);
-desc("Builds augmented version of the compiler for perf tests");
-task("perftsc", [perftscJsPath]);
-
 // Instrumented compiler
 var loggedIOpath = harnessDirectory + 'loggedIO.ts';
 var loggedIOJsPath = builtLocalDirectory + 'loggedIO.js';
@@ -704,14 +682,12 @@ file(loggedIOJsPath, [builtLocalDirectory, loggedIOpath], function() {
     jake.mkdirP(temp);
     var options = "--outdir " + temp + ' ' + loggedIOpath;
     var cmd = host + " " + LKGDirectory + compilerFilename + " " + options + " ";
-    console.log(cmd + "\n");
-    var ex = jake.createExec([cmd]);
-    ex.addListener("cmdEnd", function() {
+
+    exec(cmd, function() {
         fs.renameSync(temp + '/harness/loggedIO.js', loggedIOJsPath);
         jake.rmRf(temp);
         complete();
     });
-    ex.run();
 }, {async: true});
 
 var instrumenterPath = harnessDirectory + 'instrumenter.ts';
@@ -721,10 +697,6 @@ compileFile(instrumenterJsPath, [instrumenterPath], [tscFile, instrumenterPath],
 desc("Builds an instrumented tsc.js");
 task('tsc-instrumented', [loggedIOJsPath, instrumenterJsPath, tscFile], function() {
     var cmd = host + ' ' + instrumenterJsPath + ' record iocapture ' + builtLocalDirectory + compilerFilename;
-    console.log(cmd);
-    var ex = jake.createExec([cmd]);
-    ex.addListener("cmdEnd", function() {
-        complete();
-    });
-    ex.run();
+
+    exec(cmd);
 }, { async: true });
diff --git a/package.json b/package.json
index 9261174b68f..b53916b37b3 100644
--- a/package.json
+++ b/package.json
@@ -42,6 +42,6 @@
         "codeclimate-test-reporter": "latest"
     },
     "scripts": {
-        "test": "jake generate-code-coverage"
+        "test": "jake --trace generate-code-coverage"
     }
 }
diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index 57c2298d3d3..68507b34574 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -258,7 +258,7 @@ module ts {
             reportDiagnostic(createCompilerDiagnostic(Diagnostics.Compilation_complete_Watching_for_file_changes));
         }
 
-        function getSourceFile(fileName: string, languageVersion: ScriptTarget, onError ?: (message: string) => void) {
+        function getSourceFile(fileName: string, languageVersion: ScriptTarget, onError?: (message: string) => void) {
             // Return existing SourceFile object if one is available
             if (cachedProgram) {
                 var sourceFile = cachedProgram.getSourceFile(fileName);
diff --git a/tests/perfsys.ts b/tests/perfsys.ts
deleted file mode 100644
index 143d0d637d4..00000000000
--- a/tests/perfsys.ts
+++ /dev/null
@@ -1,105 +0,0 @@
-/// <reference path="..\src\compiler\sys.ts"/>
-/// <reference path="..\src\compiler\types.ts"/>
-
-module perftest {
-
-    interface IOLog {
-        resolvePath: ts.Map<string>;
-        fileNames: string[];
-    }
-
-    export interface IO {
-        getOut(): string;
-    }
-
-    export var readFile = ts.sys.readFile;
-    var writeFile = ts.sys.writeFile;
-    export var write = ts.sys.write;
-    var resolvePath = ts.sys.resolvePath;
-    export var getExecutingFilePath = ts.sys.getExecutingFilePath;
-    export var getCurrentDirectory = ts.sys.getCurrentDirectory;
-    var exit = ts.sys.exit;
-
-    var args = ts.sys.args;
-
-    // augment sys so first ts.executeCommandLine call will be finish silently
-    ts.sys.write = (s: string) => { };
-    ts.sys.exit = (code: number) => { };
-    ts.sys.args = []
-
-    export function restoreSys() {
-        ts.sys.args = args;
-        ts.sys.write = write;
-    }
-
-    export function hasLogIOFlag() {
-        return args.length > 2 && args[0] === "--logio";
-    }
-
-    export function getArgsWithoutLogIOFlag() {
-        return args.slice(2);
-    }
-
-    export function getArgsWithoutIOLogFile() {
-        return args.slice(1);
-    }
-
-    var resolvePathLog: ts.Map<string> = {};
-    
-    export function interceptIO() {
-        ts.sys.resolvePath = (s) => {
-            var result = resolvePath(s);
-            resolvePathLog[s] = result;
-            return result;
-        };
-    }
-
-    export function writeIOLog(fileNames: string[]) {
-        var path = args[1];
-        var log: IOLog = {
-            fileNames: fileNames,
-            resolvePath: resolvePathLog
-        };
-
-        writeFile(path, JSON.stringify(log));
-    }
-
-    export function prepare(): IO {
-        var log = <IOLog>JSON.parse(readFile(args[0]));
-
-        var files: ts.Map<string> = {};
-        log.fileNames.forEach(f => { files[f] = readFile(f); })
-        
-        ts.sys.createDirectory = (s: string) => { };
-        ts.sys.directoryExists = (s: string) => true;
-        ts.sys.fileExists = (s: string) => true;
-
-        var currentDirectory = ts.sys.getCurrentDirectory();
-        ts.sys.getCurrentDirectory = () => currentDirectory;
-
-        var executingFilePath = ts.sys.getExecutingFilePath();
-        ts.sys.getExecutingFilePath = () => executingFilePath;
-
-        ts.sys.readFile = (s: string) => {
-            return files[s];
-        }
-
-        ts.sys.resolvePath = (s: string) => {
-            var path = log.resolvePath[s];
-            if (!path) {
-                throw new Error("Unexpected path '" + s + "'");
-            }
-            return path
-        }
-
-        ts.sys.writeFile = (path: string, data: string) => { };
-
-        var out: string = "";
-
-        ts.sys.write = (s: string) => { out += s; };
-
-        return {
-            getOut: () => out,
-        };
-    }
-}
diff --git a/tests/perftsc.ts b/tests/perftsc.ts
deleted file mode 100644
index e0189896a15..00000000000
--- a/tests/perftsc.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-/// <reference path="perfsys.ts"/>
-/// <reference path="..\src\compiler\tsc.ts"/>
-
-// resolve all files used in this compilation
-if (perftest.hasLogIOFlag()) {
-    perftest.interceptIO();
-
-    var compilerHost: ts.CompilerHost = {
-        getSourceFile: (s, v) => {
-            var content = perftest.readFile(s);
-            return content !== undefined ? ts.createSourceFile(s, content, v) : undefined;
-        },
-        getDefaultLibFilename: () => ts.combinePaths(ts.getDirectoryPath(ts.normalizePath(perftest.getExecutingFilePath())), "lib.d.ts"),
-        writeFile: (f: string, content: string) => { throw new Error("Unexpected operation: writeFile"); },
-        getCurrentDirectory: () => perftest.getCurrentDirectory(),
-        getCanonicalFileName: (f: string) => ts.sys.useCaseSensitiveFileNames ? f : f.toLowerCase(),
-        useCaseSensitiveFileNames: () => ts.sys.useCaseSensitiveFileNames,
-        getNewLine: () => ts.sys.newLine
-    };
-
-    var commandLine = ts.parseCommandLine(perftest.getArgsWithoutLogIOFlag());
-    var program = ts.createProgram(commandLine.filenames, commandLine.options, compilerHost);
-    var fileNames = program.getSourceFiles().map(f => f.filename);
-    perftest.writeIOLog(fileNames);
-}
-else {
-    var io = perftest.prepare();
-    ts.executeCommandLine(perftest.getArgsWithoutIOLogFile());
-    perftest.write(io.getOut());
-}