Yes, but some consider it a compromise, while I call it a 'step toward realism'.

The best way, without having to spend a dime, is to lower the visibility, and increase the cloud cover.
I know that someone will say, "Clouds are one of the biggest performance killers", but, only with unlimited visibility.

Go to advanced weather, choose the Visibility tab, and set the tops to 99,999ft, and then set the slider to 20-40nm, NEVER MORE THAN 40!!
In real life you NEVER have unlimited visibility. So why give it to yourself in a "simulated reality'?
Increasing the cloud coverage within this reduced visibility also helps, if you're down to a 20-40 mile vis, then set the clouds to the lowest draw distance and set density to medium or Max and give yourself a nice 20,000ft tall cumulus layer to fly in.
Or best yet, always use Real world Weather. You'll soon see what I mean about NEVER having unlimited visibility, even on perfectly clear days. 8-)
The less ground texture it has to render, the less a weaker system will struggle to do so. (PERSONALLY TESTED METHOD)
This is very similar to MOUSY's 'limited focus' tip. :
http://www.simviation.com/cgi-bin/yabb2 ... 1154675513