what Virtual Private Network works best with tixati as I am having issues with slow speeds and drops in connection of my VPN I have enabled the auto limiter.The VPN clients are Private Internet Access/ Nord VPN/ OpenVPN  Any help would be grateful.

A caveat of using a VPN is that it will hamper your connection speeds to at least some extent. It's a trade-off you get for the increased privacy and security, similarly to using proxies or encryption software.

All the same, try turning off your anti-virus and see if that changes performance while using the VPN; real-time antivirus stuff often causes this kind of problem if it's inspecting the traffic which goes through the VPN. If you find that's the culprit, try lowering the anti-virus real-time scanning options or maybe try a different anti-virus.

I'll leave the advice about which of those VPNs would be preferable for other people, since I'm far from an expert.