Apologies if you get this already, but every sound being convolved plays out for the duration of the impulse response file. So if you have a long impulse you very quickly get many layers of sounds playing concurrently.
I’ve played with this quite a bit - at one extreme using a bunch of off-station shortwave as the impulse response, at the other the Funky Drummer drum loop. Sharp dynamics and shifts in the sound are most obvious if you only send short bursts at the convolution algorithm, otherwise the number of layers happening results in that slurred kind of effect.
When I played with using a drum loop as an impulse response, I sent short synth stabs into it at the start of each bar and set the tempo so this created a constant beat, with the result a bit like drums through a vocoder. The fun was then playing with the envelope of that stab - it created weird blurring effects that are really their own thing. I should go back to that track. 