So my suggestion may seem crazy but as i was working on this 0.1, it's quiet hard to see if all my power compresses, so what if i could slow tnt down to a half speed. anyways i don't know how it would work but i thought it'd be cool
I can't speak to what Cimbasso is talking about, but this is rather impractical for the cannon server. While it may be practical for a personal server it would be rather inconvenient to implement custom delta timing for specific entities based on chunk location.
There is also the issue of 32 bit floating point precision. While that may not mean anything to most people, all you really need to know is that slowed down physics may not have the same end effect as real time physics. It is possible to make this a non-issue, but you would likely be restricted to specific time scales.
In short, I wouldn't expect to see it on any of the cannon servers, but it may show up eventually as a plugin for personal servers.