Netbeans - Turn off - wavy red underlines - How?
No correct solution
This has actually already been addressed and illustrated in Arnold's answer to NetBeans. Disable error checking underline (+1); select Tools -> Options -> Fonts & Colors -> Syntax -> Category Error and adjust the font effects (or any other style) to your liking:
I've confirmed it to still work like so - please note that new settings won't have any effect until you trigger an editor update, e.g. by typing a letter.
Unfortunately this doesn't seem to help with performance in any immediately observable way (though removing font effects like this indeed used to speed up things in the olden days).
Follow this path if you want to turn them off, (I'm using NeatBeans 5.5.1)
Tools -> Options -> Advanced Options -> Open the "Editing" node and click on "Java sources" -> Enter 0 for the "Error Annotation Limit"
That will completely turn off the red underlines. You can also change the "automatic parsing delay" at the same location if you want a longer pause instead.