Hi,
Whenever I use Media Player Classic HC, it is slow to start (a few seconds). I have determined it is due to Avast Free scanning the program as it starts. When I disable the scan program when executing, it opens instantly. This since v6.0.1289. Have updated to 1367 but same issue. Thanks.
btw, is there a way to exclude only MPC-HC from being scanned rather than disabling scanning of all programs when executing?
are you using Comodo Firewall?
may be Defense+ conflicts with Avast
you found out Defense+'s logging that you can see a “AvastSvc.exe” event close to “MPC-HC.exe” event
you need set “AvastSvc.exe” to “installer or Updater” (in Comodo Defense+)
In the File System Shield, you could add the relevant exception / exclusion to the specific executable file.
To be clear, I am NOT recommending this. I am just answering to your technical question.
To kvl, I’m not using Comodo firewall. 
To ady4um, I think I got it. I had seen the exclusion tab in the file system shield options but had figured it only applied to the regular scans avast does and by folder/directory exclusion rather than specific programs. Anyway I excluded the directory mpc-hc is in and it seems to have worked, its functioning normally now. Thanks. 
avast can exclude both folders AND single files/executables, just set the right path for them.