Amiga bus frequency max?

[ElPolloDiabl]

The Zorro bus on an Amiga 2000 is 7mhz at 16-bit.
Not sure about Zorro III, but it varies.

The chipset is mostly sound and graphics and can't really be sped up. If you add fast RAM/CPU RAM this takes a load off the chip RAM and gives you a speed up.

Are you asking about bottlenecks? E.g. You have a fast graphics card, but after a certain point it starts to slow down. This would because the Zorro bus can't feed enough data from the CPU to the graphics card.

Sometimes a faster CPU might give you a speed increase. It depends on whether a task is graphics intensive or CPU intensive.

If you want faster you have to get as much of your expansions close to the CPU. The IDE interface on an A1200 is particular slow, put it next to a fast CPU and it would be doing 10 Megabytes a second or more.

It's old hardware so I guess there is no point in trying to squeeze more out of the chipset.

[ElPolloDiabl]

For access to chip ram it's 7mhz for OCS/ECS & 14mhz for AGA. The CPU only gets spare cycles, so the limit is irrelevant to whether there is a CPU or not.
 
The CPU only has access to Agnus, which has it's own register bus that connects to paula and denise. I believe the register bus runs at the same speed as chip ram.

I think I read somewhere that it can access Agnus at 28Mhz.

[ElPolloDiabl]

Actually it works at 28mhz internally as a co-processor. That sounds right.