Thank you very much,
Only Java was out of date (and I don’t understand why because Java opened last week because of an update and I updated it !).
Disabling Flash hardware acceleration doesn’t help much 
I don’t understand
I know I already wrote that, but with KASPERSKY that is a very heavy antivirus, I don’t have any problems, the videos load very fast.
About KAV remover, I tried in safe mode. I had problems because of KASPERSKY AV being heavy, someone from the KASPERSKY forum advised me to uninstall the AV and install it again, so he told me how to use KAV REMOVER and told me to use it in safe mode. But it doesn’t work.