Slow syntax highlighting

[ci70]

• VSCode Version: Insider 1.30
• OS Version: Windows 10 1607 LTSB x64

Steps to Reproduce:

1. Load large C++ file (60k LOC)
2. Observe the slowness. Takes like 10s to highlight the code.

Does this issue occur when all extensions are disabled?: Yes

[alexdima]

Today, syntax highlighting is running on the main thread and is implemented by constantly yielding in order to keep the thread responsive. The speed is further influenced by the grammar. This can be improved if we move the tokenization to a separate thread.

[ci70]

Excellent. Hope to see it implemented ASAP.

[ci70]

Is fix coming? @bpasero
https://www.youtube.com/watch?v=nDRBxtEUOFE

[ci70]

Has this been fixed?! It's been almost 9 freaking months!!!

[matter123]

@optomux I co-maintain the C++ grammar if this still appears broken, could you create an issue in https://github.com/jeff-hykin/cpp-textmate-grammar with an example file that reproduces. Alternatively, if the file is confidential, I can provide steps to collect performance information without revealing the file.

[ci70]

Open sqlite3 which is pretty large.

[matter123]

@optomux After processing the 223k loc sqlite.c There does not seem to be much that can be done on the grammar side. While it did take 11.7 seconds to evaluate the patterns inside the grammar, no individual pattern took an unexpectedly long amount of time.

If you are having similarly long times on significantly shorter files, there may still be an issue in the grammar, however.