Somewhat off-topic but related - I’m experiencing a similar issue where the editor becomes extremely slow when a form with many lines of code is open in code view (or split view). The editor takes 3-4 seconds to register a single keystroke. Moreover, the entire editor becomes slow (i.e., working in other forms/modules) so long as the form in question is open as a tab.
I work around this by working in my local IDE and pushing to Anvil. However, I’m curious if there might be any fixes.