If i download mods for Minecraft, will it slow down The Sims 3?

Hi. Ihave minecraft and the sims 3 installed. I have custom content installed in the sims 3. It lags sometimes but rarely, and it takes a long time to load. I want to download mods for Minecraft but if i do download mods for minecraft will it make The Sims 3 even slower.

No it won't as the two games have nothing to do with each other as long as you are playing 1 at a time short answer: no

Depends on your computer really. If you were having lag while playing the Sims 3 even before you installed the mods for Minecraft, I doubt that would help performance. It shouldn't be too big of a deal though, unless you downloaded a very big mod. If any of the 2 games perform very badly, try deleting some program you don't use.