Firstly I am a big fan of MB. I have had a problem and tried other players but always come back to MB. The only issue I have had is that on my desktop, very consistently, the programs takes 2 minutes and 45 seconds to load (+\- 15 sec) I also use MB on a laptop and it loads in 5-6 seconds. I have tried many things, disabling AV, reloading program, I even transferred the configuration from the laptop to the desktop without any improvement. I actually think it is related somehow to my Windows but other programs don't seem affected. Anyway its a relatively small problem everything else works great.
I have looked a few older posts here about slow startup but nothings seems applicable to me.