VS code feels slow. All of a sudden, saving took forever in a TS project. The first suspect was a recently added WallabyJS test runner extension. So I disabled all plugins but still, saving took several seconds. My head then turned towards TS. Arrogantly I blamed some dependency but I had not a clue which one. Github TS wiki has some tips and tricks on what to do, including instructions to run a profiler. Turns out, a new profiling tool was introduced not too long ago in TS 4.1. The output looks like this. Compiling the slowest source file takes more than 7 seconds! There is one massively slow checkSourceFile call which, as the name says, compiles a single file. To my embarrassment, it was in my code 😱 The profiling output is rather hard to decipher. The UI shows which TS internal functions are called and references a separate JSON file containing the type names. In my case, the slow function(s) included some weird single character type names, so it was not much help. The arguments
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