Freeze while finding/replacing large amount text

[cassidyjames]

I attempted to replace tabs with spaces in a ~6000-line tab-indented file. Code's UI locked up pretty much immediately, and a single CPU core was pegged for a couple of minutes. After a few minutes, Code had performed the replacement properly, but it had rendered the whole app unusable in the meantime.

For kicks and to reproduce, it was this file: https://github.com/elementary/wingpanel-indicator-network/blob/ce10f927cc7adb4843aafa536b12968bd512883b/vapi/libnm.vapi

[vaclavhlobil]

Same with one-line file. Try to open XML without line-breaks (all the code on one line) and try to find ie. "<" string. Unusable.

[it-s]

Confirm same behaviour for minified java-script files. The interface becomes slow and unresponsive.

To reproduce open https://code.jquery.com/jquery-3.3.1.min.js in code