Resolve 16 Performance Issues

Hello all
I'm still pretty new to Resolve but I have a fairly large project to accomplish now and Resolve seems to be giving me the "spinning Lollipop" a lot.
I'm working on a promotional video for a friend of mine that has about 30 'pieces to camera' by the presenter plus a sync cutaway (2nd camera for most of them, as she is demonstrating things.
None of the clips are more than 2 mins long but in the interests of logic, and I hoped performance, I have divided the footage up into the individual bits and put them in Bins.

Typically a bin will contain the Main Camera view and the 2nd camera view.
I've found the Multicam sync facility brilliant at syncing with sound so I can create Multicam timelines.

I am editing each sequence separately on it's own timeline and rendering it to disc.
So eventually I will have about 30 Timelines - at the moment I have 4
In the media Pool I have about 35 Bins with the relevant clips stored in there,
I am using a Mac Pro to edit OS 10.14.6 6 Core 3.33Ghz 48 Gb memory, Radeon RX 580 Video Card and everything is on an a separate internal SSD

My computer is kinda old; mid-2010 (but loved) and usually its spins thru Resolve edits without much trouble.
Now it is really showing signs of strain; just hitting the play bar results in a delay and spinning lollipop

Is it the way I have set up my project that is causing the slowdown or something else.?
I had specifically chosen multiple timelines to edit all the sequences - is that a bad idea ?
But I only have about 4 at the moment - if that's the problem what's it going to be like when I have 30 ?
I'm editing in 1080p (I'm not making a Hollywood blockbuster just some internet fodder)
Why is everything grinding to a halt ?
Your advice would be really helpful
Thanks

[Peter Chamberlain]

A 10 year old computer will be taxed.

How long are each of the timelines?

If you have rendered timelines, 30 of them for example, and you add 4 to a new timeline and it slows down its clearly a problem.
Check if there is a better GPU driver for that card, and that you have OpenCL selected and are using the RX580 and not a motherboard GPU
or
Try starting a new project and just import the rendered timelines.

Each Timeline is less than 3 minutes.
I have rendered a couple so I can show my colleague how we're coming along.
Then I start a new timeline for the next sequence - thereby leaving the timeline in the Bin with the sequence.
I was thereby expecting Resolve only have to do the brain work on one sequence at a time.

Two sequences have been a green screen master shot and a second camera supplying close up cutaways assembled into a multicam sequence.
Having edited the multicam sequence I then use Fusion to cut the mask on the green screen and colour grade using the Colour page.
It actually works well but it is irritating to have to do the greenscreen matte for each clip when I know they are in actuality all part of the same clip.

Would "Optimised media" help do you think ?

Re the card: having installed the RX 580 I have noticed a big improvement in Photoshop but how can I be sure Resolve is taking advantage of it?

Thanks for your help

Re: Optimised Media
I was checking on You Tube and came up with this:

Guy is advocating the use of "proxy" files but it looks rather complicated.

Does that look to be a viable alternative to optimised media.?
I don't want to screw up my project on a wild idea. !

Proxies are the way to go, check out 17!

Hi Uli
I notice you are using the Radeon580 in your Mac
I have that installed in my MacPro (2010)
I am assuming that you are having success with that as you seem to be an accomplished editor.
Is there anything I should be looking for in my settings either on the Mac or within the preferences on Resolve 16 that may be hampering the performance ?

I'm afraid it is not much you can do about it if most of your sources are H.264/265. Unfortunately, the XEON CPUs are missing the Intel decoder units, which my iMac has (like all iX Intels). If I'm right about your sources, you can only transcode.

The Radeon 580 is helping with many other tasks, but not the decoding.

i would do 2 things to do better on the old cheese grater

first, a PCIe card with NVMe device for the data (single speed 1400mbps)
second, opencore to enable the hardware acceleration of the RX580 for H264/H265 decoding/encoding

Opencore ?
Can you explain ?
(as if you were talking to a 10 year old !!)