Extension causes high cpu load

[YannisFraselle]

• Issue Type: Performance
• Extension Name: marp-vscode
• Extension Version: 0.12.0
• OS Version: Windows_NT x64 10.0.18363
• VSCode version: 1.42.0

-> marp-team.marp-vscode-unresponsive.cpuprofile.txt

Find more details here: https://github.com/microsoft/vscode/wiki/Explain-extension-causes-high-cpu-load

[yhatt]

It seems to be taking a lot of time while reading Marp Core from disk. As suggested by VS Code, it can mitigate by bundle Marp Core into extension with using rollup but would not work the extension due to the incorrect build caused by the circular dependency by PostCSS.

It has been fixed in postcss/postcss#1321 but the new release (PostCSS 8) is still not coming.