TJ Hooker :
@nilesb5 none of that would have a significant impact on gaming performance unless there was something else wrong with your PC, like a rogue process consuming resources. For instance, simply having groove music installed is not going to have any effect on performance. Defender isn't going to impact performance unless it's trying to actively run a scan or something. Etc.
Yes Groove was a bad example of all the bloatware preinstalled on most systems these days. Symantec brags their antivirus has the lowest CPU drag for real time scanning of "only 4%" whille Defender is higher, run a before and after test with and with it disabled to see. I could have gone into a 40 page answer with optimizations like MTU sizing to avoid packet fragmentation, Indexing, Superfetch, disabling 8.3 filename support and last modified file stamping, reducing transmit and reciever buffers if your CPU is fast enough to handle the more frequent refreshes, and the million other things, but this was a simple answer for someone just starting out. Likely someone with a name brand system loaded to the gills with bloatware. Less is more is the best short answer, so many good, specific tutorials are out there for getting deep into the details for gaming performance.