I have been wanting to move my site and client sites to a new hosting service for over a year, as I felt the speed and up-time with that of the previous hosting provider could be better.
Well... I had the time and have just moved my site to a new host and to a shared hosting plan with the data center (servers) located in the U.K.
I spent a few minutes testing both the user and admin side of WordPress that runs this site and which uses a few plugins and a theme with many admin features.
Plugins and a complex, or feature rich theme, can slow both the user experience, and also the administration of WordPress sites. However, on first tests, all I can say is that the site works super fast compared to the previous host, and it feels faster, as if having cloud hosting or dedicated hosting.
I am happy with the initial tests, and am now going to start preparing to move all my clientss managed hosting sites to the new servers, with no additional fee to the client.
I'll let you know who the new host is after a bit more experience and site moving.