This has already been reviewed and illustrated in Arnold's answer to NetBeans. Disable underscore check verification (+1); select Tools → Options → Fonts and colors → Syntax → Error category and adjust the font effects (or any other style) to your liking:

I confirmed that it still works like this - note that the new settings will not have any effect until you activate the editor update, for example. typing a letter.
Unfortunately, this does not seem to help in performance using any instantly observable method (although removing font effects like this is really used to speed things up in the old days).
Steffen opel
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