If I download a song from the Share platform, will my computer slow down even if I delete the download?
Your pc efficiency / speed should not be influenced of any project in significant fashion.
Some project may use a lot of VSTs, but i have run 50 on a mediocre pc just fine. Lmms will normally act nice and release all used resources when you un-load a project, but some issues with a few VSTs has been reported over the years.
You can check if any process of remoteProcessVST is running in TaskManager, and then shut them down manually, that should clean out everything
Besides that, since i cant remember to have seen you in Forum
Welcome Onething !
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules (Including that we are an english speaking community Google translate will do just fine:) and useful forum instructions
If you like to introduce yourself, to the community, go here:
http://lmms.io/forum/viewtopic.php?f=4&t=4480