Performance issues when upgrading node-sass version

[mtrajano]

• NPM version (npm -v): 6.11.3
• Node version (node -v): v12.12.0
• Node Process (node -p process.versions):

{
  node: '12.12.0',
  v8: '7.7.299.13-node.12',
  uv: '1.32.0',
  zlib: '1.2.11',
  brotli: '1.0.7',
  ares: '1.15.0',
  modules: '72',
  nghttp2: '1.39.2',
  napi: '5',
  llhttp: '1.1.4',
  http_parser: '2.8.0',
  openssl: '1.1.1d',
  cldr: '35.1',
  icu: '64.2',
  tz: '2019a',
  unicode: '12.1'
}

• Node Platform (node -p process.platform): linux
• Node architecture (node -p process.arch): x64
• node-sass version (node -p "require('node-sass').info"):

node-sass	4.12.0	(Wrapper)	[JavaScript]
libsass  	3.5.4	(Sass Compiler)	[C/C++]

• npm node-sass versions (npm ls node-sass): [email protected]

Hello and thank you for maintaining that awesome package. I originally posted this issue in the libsass repo and they told me it would be worth it to x-post here as well for reference, original issue: https://github.com/sass/libsass/issues/3054.

To summarize: We run an application where we do a lot of sass compilations on request. When we upgraded our systems to node v12.12.0 along with node-sass to v4.12.0 (libsass v3.5.4) we noticed a decent performance degradation (our response times nearly doubled). We eventually pinpointed the response time slowdown to the node-sass upgrade and when when we did a rollback of the node-sass version alone to v4.6.1 (libsass v3.5.0.beta.2) response times dropped significantly, back to it's normal levels. I will be running some tests on the libsass versions directly using the sassc wrapper to try to drill down the problem further but either way the libsass team said this is probably not something they will address as they are working on libsass v4 which apperantly brings a lot of performance boosts to the library. Either way we really appreciate the effort that goes into maintaining this package and we hope to hear back from you soon, thanks!

[chriseppstein]

possibly related: I've noticed significant performance issues when using map-merge() on large maps.

[saper]

Would that be possible to have some code to reproduce this?