Hm. It really seems to have something to do with FSUIPC. Because everything went fine until I installed Radar Contact today. The same problem resurfaced, both in FDC and Radar Contact - extremely long response times and loss of connection between FSX and the program.
Here's what i posted in the FSUIPC support forums:
Hi,
I have a problem that might be related to Radar Contact or FSUIPC, but I am not completely sure.
I installed FDC Live Cockpit V3.90 lately.
Installation went fine so far. FDC tried to install an old version of FSUIPC, but discovered the newer one (4.5.3.0) on my PC, so it didn't.
The next thing I get during installation (FSUIPC4 Installer for FSX) is a warning window saying: Problem! My signature check fails on the installed FSUIPC4.DLL. Please check that I am not listed as an untrusted publisher in Internet Explorer. Then I have to reconfirm my registration numbers and FDC is properly installed.
Now, FDC Live cockpit runs without problems but one: The checklists take ages to load, and during the checklists the menu entry in FSX disappears until the answer is spoken (takes up to 30 seconds instead of instant reply).
I managed to get this problem away (but don't know how, really, I allowed FDC to communicate through the firewall, then it was gone). But today I installed radar contact. It also tried to install a version of FSUIPC, discovered the newer one and then didn't install FSUIPC. This time, I didn't have the warning box.
But now Radar Contact and checklists in FDC are slow again. Radar Contact takes as long to react as the checklists from FDC do. Firewall settings do not help now.
OS is Vista 64, onboard Realtek HD audio sound.
Both FSUIPC and WideFS are latest versions, as are Radar Contact and FDC. I am totally at a loss here, what do you suggest that I do?
Thanks for your help in advance,
Bernhard