what to s"show in Imap" to stop poor performance

Having a problem with the amount of time spent “downloading messages.” So often I’ll click on a message and get the result that the message hasn’t been downloaded - even though I’m currently online.
Seems to be stuck on downloading or synchronizing.
Right now it seems to be stuck on Synchronizing [Gmail]\Spam

I tried “Download messages for offline access” but that seemed to cause the synchronization problem to take even longer.
Do I have the correct settings in “show In Imap” for gmail?
I believe I was told that I need to always check "All Mail"
Does google limit the amount of mail that can be uploaded/downloaded in one session?

I’m looking for the correct settings in Gmail and Email Client to deal with this.
What should “Show in Imap?”
Why does “Download for offline use” cause slow synch

7.1.31024.0 Licensed pro version on PC Windows 10
Gmail: Google Apps standard 50% of 15G used.
I have an android phone and 2 desktop PC’s connected to the account.

Show in IMAP:
Sent Mail
Spam (tried shutting this off - no help)
All Mail