Zoom slow on paid account but fast on free account.

Hello.

I am a teacher for my private classes, I have a paid zoom account.  When I use it all my computer is slow.  
pressing “participants” button, “screen share”, “mute” it takes over 10 seconds to register.  Sometimes not at all.

This is even before anyone has joined or in waiting room.

i have a free account provided by a subcontracting company.  That is fine.  No issues. Smooth and fast.

I used paid zoom in Aug/ Sep and it was perfect.

I restarted again in Feb/March, now it is so slow….

It is the same PC as before and last time.

any ideas?

i also use a free