Hi Patrick. Thanks for the welcome. I haven't been able to do much, as I'm just the site owner and don't have access to error logs or other admin features. What I can tell you is that the library's default view only takes a few seconds to load, and nothing (e.g. workflow) happens on form submit.
Also, I just heard from our tech support group today that the problem is likely stemming from some updates that were run on the server. They didn't give details, but I hope that something went wrong, and once they fix it we'll be back at normal running speeds. I'll post back here if there is anything helpful to share with this forum.
Btw, thanks for the link to that DBXL service. It sounds impressive, but we have a very buttoned-down environment and I'm sure it would never get approved
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UPDATE July 21 2010: FYI, our problem is resolved. I never did get a technical answer on what went wrong. Our support group only told us that the problem was caused by some updates on the server, and recent additional updates have restored the library to the original submit speeds.