We have had the same problem. I've asked our FM consultant to take a look at some of our settings and calculations. I read somewhere that the secure connections feature under Server Security could slow things down a bit. But we don't use that setting.
We have also changed some of our calculations, but they didnt cause any problems in FMS13, and the slow performance doesn't seem to be related to scripts or calculations. It could also stall for 10 secs just when scroolling through records.
I have also read about the secure connection feature, but we are not using that either.
We are using the 14.0v2 update.
We did a clean install on new hardware, with at clean Windows 2008 R2 installation, and still same problems.
Unfortunately we have now tried everything, and our next step will be to downgrade to version 13 again, because currently the system is close to unusable.