5 Loaves & 2 Fishes

Gmail has slowed down to a standstill in some cases and very slow in others.
Browsing gmail.com takes forever
This has been going on for about 2 months now

The facts are (for me at least):
I'm running a TCP/IP ethernet network consisting of 5 subnets and a total of close to 300 users, mostly PCs but quite a few WIFIs and private home networks
Many are complaining about slowdown of gmail. some can't GET, some cant SEND
Testing I found that firefox works fine where as at the same time IE(8) is hopeless.

I know we have been blacklisted as a community because of a virus attack that was SMTPing quite a bit of mail. I've since, shut down any SMTP activity short of our legal ones and we have been removed from many if not all, blacklists.

So, does anyone experience anything with gmail lately?
Is there a world-wide battle going on? MS vs Google? Maybe China are involved having that big issue with Google?

I know this is a big thing if it IS worldwide and 5L&2F probably don't have the tools needed for this, but I need to know if it is beyond our network

So.....anyone have anything on this?

Thanks - David

(Added in: We have our own (Linux) server mainly for email, hosting and proxy. We have our own firwall and network manager)