That's fine, by the way I was using medium quality overcast which gave me lower frames than default clouds.

Speaking of overcast, I took a few other screenshots yesterday and had some interesting results.

 

There was some poor weather around Cincinnati yesterday so I loaded up the sim at KCVG with X-Plane's default real-weather enabled. Here is local map and weather info, followed by a pair of shots facing the NNW.

 

 

1) Default XP real-weather, default XP clouds

 

 

2) Default XP real-weather, Skymaxx Pro 2.0

 

 

I enabled UltraWX moments later. The local map isn't much help with distinguishing the cloud formations since XP is drawing the overcast layer across the entire map (something it doesn't usually seem to do with its built-in engine (see the above map)).

 

 

3) UltraWX, default XP clouds

 

 

4) UltraWX, SkyMaxx Pro 2.0

 

 

This time the weather source data for both UltraWX and X-Plane's real-weather appeared to be very close to each other, as reflected in the screenshots using default clouds (images 1 and 3). What's particularly interesting, though, is that while using UltraWX, the injector appears to be able to substitute SkyMaxx's stratus clouds (image 4; I believe this is also the same as the "low" quality overcast in the SkyMaxx options) for the "patchy" cumulus overcast that SkyMaxx depicts under the default real-weather engine (image 2).

 

Also, here is the actual METAR data from the airfield at the time:

METAR KCVG 101552Z 11006KT 8SM SCT013 OVC100 25/20 A3003 RMK AO2 SLP157 T02500200

Alexcolka:

 

Courious did you try turning deleting the settings.dat inside smp? Also leave god rays and maybe even cloud reflections off? Plus turning down the cloud draw distance is another boost....This kind of tweaking can have huge gains over the defaults with little impact on the overall appearance of smp....

Jspahn, yes I tweaked a lot the options, not using god rays nor cloud reflections and cloud distance is at half but thanks for your observations. This performance decay is only with two cloud layers mostly (one being overcast with med texture setting) using real weather.