Hmm, not too sure on this one. Is it possible your account is trying to make a connection on a port being blocked either locally or on your setup? Do you have CSF installed or any backend firewall from a provider? The SSL certificate warning is usually just a default message and in most cases can be ignored... which brings me to...
Those SSL certs are built in by default on the install of the apache stack. I wouldn't advise removing SSL from your server simply due to it's encryption being a "must for most" sort of thing.
I'll fire up a quick demo instance today and see if I can replicate a slow connection via the
quickVPN install. It's possible this could simply be an issue between yours and your servers location as to why the VPN would be slow... but I won't know until I check.