[Hummingbird] Website running slower since adding WPMU DEV

Hi there,

Newbie here, not sure if I'm set up correctly so thought best to ask. I've just gone pro and added Hummingbird to my site after previously using W3 Total Cache and Autoptimize (thought I'd test it out before rolling it out across my other sites).

Prior to the switch I was hitting:

2.249s

PageSpeed Grade
A (96%)

YSlow Grade
B (89%)

Now I'm getting (with Autoptimize still installed):

2.224s

PageSpeed Grade
C (78%)

YSlow Grade
C (77%)

Obviously I don't want to get hung up on the grades but ideally I'd like to hit the grades that I know I can achieve. Keen to learn my way around it but from what I can see so far I have done what I'm supposed to.

Things that jump out at me that are bad grades - Enable Compression F (0%). On my Hummingbird dashboard it says that this can be improved (currently at 60%) but when I go through to improve it it says "GZip compression is currently active. Good job!". Stumped on this one.

I'm also getting "Use a Content Delivery Network(CDN) - F (0%)" and "Make fewer HTTP Requests - F (0%)". In my asset optimisation it says - "WPMU DEV CDN is active" again I'm stumped. Hummingbird side is showing "Remove render blocking resources" - 69% - "Your page has 11 blocking script resources and 13 blocking CSS resources. This causes a delay in rendering your page." but fixing this is a little out of my league (I am a designer/front end guy).

Apologies for the long read but any help would be greatly appreciated. Thinking WPMU DEV will be a great asset across my sites so just want to get the best possible results. Keen to hear everyones thoughts.

Thanks so much,

Zak