Last time I checked, DDR5 and DDR4 latency was basically the same. Very little progress there. May be with integrating DRAM and CPU on the same package, some latency wins will be available just because wires will be shorter, but nothing groundbreaking.
My DDR4 was C16, but my DDR5 at C30 makes up for that with sheer speed.
Currently sporting this -
G.Skill Trident Z5 Neo RGB Black 64GB (2x32GB) PC5-48000 (6000MHz) with a 7800x3d.
Previous kit was G.Skill Trident Z Neo RGB 32GB (2x16GB), PC4-28800 (3600MHz) DDR4, 16-16-16-36 [X2, eventually, for 64 total] with, you guessed it, the 5800x3d, from the 3900xt - my son loves it.
To reiterate the GPs point, in case anyone didn't get it: DDR4-3200 CL16 is equivalent to DDR5-6000 CL30 or DDR5-6400 CL32 in terms of latency. Divide the frequency by the CAS latency and you get the same number for all of those. It was the same situation going from DDR3 to 4. There's some wiggle room if you run above-spec voltages (and depending on the quality of the chips, etc.) but things have stayed roughly where they are latency-wise, gen-to-gen.
True! I realise that I left it unsaid in the numbers. Granted, herz for herz my DDR4 3600-CL16 had even better latencies than my DDR5 (4.44ns vs 5.00nz) - but for overall performance the speed then tends to make up for it (assuming a varied workload).
I've actively shopped for low latency RAM - within reasons, but have paid good premiums especially in DDR4 days. For DDR5, there can be surprisingly little price wise to differentiate e.g. CL30 or CL32, so whilst it may not offer the greatest of differences, if you're already paying e.g. $350 (AUD) for a kit at CL32 the improved latency might just be $20 more at the same speed.
(I see that things have moved on a bit from last September when I did my last upgrade; now we have CL32 at higher speeds, so maybe that's the go to now.)
There's another factor, which is the number of independent channels; DDR5 doubles the number of channels per memory stick. This gets more important as CPUs get more and more cores.
Yes, latency has stayed fairly constant going back at least as far as DDR3. It was nudged downward a little from DDR2 to 3, with higher clocks bringing finer grained timings, but I would say any improvement in later generations is pretty negligible in nanosecond terms.
