Maybe there could be a much less 'dense' smoke effect made. It can block vision and lasers for all intents and purposes with the combat rules in the game, but visually make it a shallower effect. The original XCom just had a few pixel trails in each square, which was simplistic but it let you know there was smoke there and that it was working. The current smoke looks like a very 'dense' effect, maybe it draws too many resources on certain rigs and drivers. Can't be sure, just tossing a possible idea.
I also remember older games using alpha blending back in the day, take a solid image and it goes partially transparent without using too much hardware resources for many effects. I know for sure Homeworld did this, but seen the option on quite a few other games before multi-core CPU's hit the market.
