exchange 2010 with 5 instances w3wp.exe

I have exchange 2010 sp3 running on 2008 r2 with all roles installed.

We are having latency issues where Outlook is hanging or working slowly. Users get frustrated and click away, crashing outlook, then outlook hangs and they think windows has crashed etc etc etc

The server is low on memory and more has been ordered. However up until sp3 was installed no issues where reported. Over the holidays we installed sp3 and since then have installed all updates.

There are 30 users with a mailbox database hovering around the 100gb mark. Store.exe is running around 2gb's of memory but that fluctuates.

I also have 5 instances of w3wp.exe running, each consuming about 160mb, 160mb, 260mb, 260mb, 380mb's. I can't say for sure they were not there before the sp3 install but I don't believe they were.

Does that seem normal for this type of server to have that many w3wp.exe instances using that much memory? I've read a lot about w3wp.exe taking a lot of memory but those were supposed to be fixed in sp3.