Interesting question. I imagine the other drug in question would affect the answer. Like does it require the same enzyme for metabolism ? I would think that as far as calories go the increased heart rate would also increase energy consumption... but I don't really have a good answer for the breakdown of other drugs... Hopefully somebody else knows!
Meth and most stimulants will speed-up your general metabolism (your body will consume more calories, etc.).
But drug metabolism is kind of a different thing (it mostly takes place in the liver).
Meth could potentially interfere with other drugs that are also metabolized by CYP2D6. But if anything, it would likely make them last longer since both drugs would be competing for the same enzyme (and the other drug may also slow down the metabolism of meth).
I can't say for certain, but I've mixed meth with a few things and never noticed any impact to duration of those other substances. Substances like LSD, mushrooms, heroin and fentanyl to be exact. I noticed that the LSD high isn't shit when using meth, like it blocks it from its full potency somehow. Same duration though. Mushrooms I microdosed and everything seemed as normal as can be while mixing shrooms and meth. H and Fentanyl have both put me from being as high as a kite on some good meth to nodded out and waking up sobering up hours later.