I have the same problem in P3D v4.5.
Last week, it worked somewhat. This morning, I could not open the GSX menu with they key command or the menu entry. MSFS works fine though...
I run the online updater every day and the current offline updater after that.
Airport cache regeneration completed with success in 91 seconds
GSX SimStart
Creating model cache...
Loading airport EDDM from F:\Program Files\Lockheed Martin\Prepar3D v4\SimMarket\TAXI2GATE-EDDM P3Dv4 P3Dv4\data\EDDM\scenery\EDDM_AF-SODE.BGL
Loading user customizations from C:\Users\denni\AppData\Roaming\Virtuali/GSX\eddm-cartayna-v4.ini
Traceback (most recent call last):
File ".\common\modelCustomization.py", line 949, in setJetwayAirlineCode
File ".\common\modelCustomization.py", line 993, in getModelForCouatlType
File ".\common\modelCustomization.py", line 962, in getModelsForCouatlType
File ".\common\criticalsection.py", line 23, in _synchronized
File ".\common\modelCustomization.py", line 763, in _cache
File ".\common\modelCustomization.py", line 832, in _loadCacheFromPath
File ".\common\modelCustomization.py", line 904, in _loadLiveriesForModel
File ".\python27\ConfigParser.py", line 350, in items
File ".\python27\_abcoll.py", line 565, in update
File ".\python27\collections.py", line 93, in __iter__
RuntimeError: this tasklet is taking too much time to execute
{'Airport': 'EDDM', 'User Pos': (48.35786886522291, 11.792549696264018, 457.33 m, 4.09384 m, 263.86987265322193, -0.0001686788455117494, -0.00017453292093705386, -0.0, 3.98068812789917, 1.0)}