Performance Slowdown from TSLint 3.x to 5.x

[danbucholtz]

I am working on updating Ionic Framework apps to go from TSLint 3.x to 5.x. I have noticed a significant performance slow down when working in the same environment.

With version 3.x, we consistently see lint operations complete in about ~1.25-1.4 seconds.
With version 5.x, we consistently see lint operations complete in ~4 seconds.

This is with the exact same rule set (minimal) on the exact same project (same source, etc).

Here is our default tslint.json config file. Here is the code we currently use for running TSLint (3.x). Here is the proposed code for TSLint 5.x.

What else can I provide to help you triage and resolve the issue?

Thanks,
Dan

[ghost]

So you're only using 2 lint rules?
no-unused-variable now creates a Program so it can use TypeScript's implementation (#2235), which may explain the slowdown there.

[adidahiya]

Yeah, I don't think there's much we can do here. You can bring back the old implementation of no-unused-variable as a custom lint rule, but we're not going to do that in core TSLint. As usual I'm going to recommend migrating to the tsc options noUnusedParameters & noUnusedLocals, if possible.

[danbucholtz]

Creating a program is a synchronous operation, correct? Perhaps we can work with TS team to provide an async option to speed this up.

Thanks,
Dan

[ghost]

I don't think that would provide a huge benefit because TypeScript doesn't spend much of its time in I/O.