needs_script is slow sometimes (in MacVim?)

[comex]

After upgrading LustyJuggler from an old vim.org version, I noticed that there was a notable lag between pressing the key to run :LustyJuggler and the menu actually appearing, but only in MacVim - on the command line it was fast. Long story short:

• Stubbing out needs_script? fixed the lag (regardless of the return value).
• The lag doesn't come from time spent actually running the script - profiling showed that it always exited promptly.
• Instruments suggests that the time is spent redrawing (even though the output is supposedly being redirected). Since needs_script? is executed 7 times for each key mapping, it would make sense for the lag caused by this to be noticeable.
• This may or may not be related, but if the call to print_buffer_list is commented out, I get a list of bindings for some reason. I didn't figure out which command is causing that, but it seems odd.

[sjbach]

Thanks for the bug report and investigation. It's not immediately clear what the issue might be; I don't have this issue with MacVim. What version of MacVim are you using?