If you don't mind not seeing the other folders (labels) then you can go to your Gmail webmail and Settings>Labels and uncheck "Show in IMAP" for the folders you don't want.
One thing I did was to "archive" older email in gmail. It's still searchable in the gmail web interface if I pick "all mail" instead of "inbox." Apple Mail on OSX, Airmail on OSX and Mail on my iPhone and iPad work MUCH better with my email over 1 year old archived. At first I liked having search bring up stuff from 2001, but I began to realize I almost never needed anything more than a few months old and when I did, I didn't mind going to gmail web interface to find it.
If you don't mind not seeing the other folders (labels) then you can go to your Gmail webmail and Settings>Labels and uncheck "Show in IMAP" for the folders you don't want.
Thanks for this tip. I looked and indeed it is there under settings. I might have gotten away with simply unchecking "show in IMAP" for labels I had put on older mail. For now, using gmail's "archive" feature has improved gmail performance on every platform I use, but I'll keep this method in mind as well.
If you don't mind not seeing the other folders (labels) then you can go to your Gmail webmail and Settings>Labels and uncheck "Show in IMAP" for the folders you don't want.