No issues here with Win10, or the latest updates.
Admittedly, my 2007 daily use laptop did need a tweak to make the WiFi card compatible.
I would say as long as you don't have incompatible hardware, Win10 runs as faster as Win7 on any Intel based machine. If you bought AMD, well, serves you right really.
I would suggest, once upgraded to Win10 (and thus having the free licence), to rebuild from scratch - this will force out all the left-over shite and OEM shite from your Win7/Win8 original builds, which are the mostly likely culprits for any incompatibilities.
As BM says, Windows Defender on Win10 is more that adequate for AV. Possibly worth running a Malware Bytes Free scan weekly to remove non viral malware.
As to OSX v Windows 10 performance, there's not a huge amount in them on the same machine. In many cases, Windows may just have the edge, due to more optimised drivers. Obviously, AV software hurts both platforms, especially when accessing disks, though as BM states, MS SE/WinDef is pretty lightweight when it comes to resources.