To contribute to the current debate about the "ideal" particle size range (sub-2 mu m vs. supra-2 mu m), the present study compares the kinetic performance of some commercially available sub-2 mu m and 3.5 mu m particles used under quasi-adiabatic conditions via the kinetic plot method. Under the adopted assumption that viscous heating effects can be neglected (which is uncertain in a pressure range above 400 bar), the obtained kinetic plots show that, provided each particle size is used in a column with properly optimized length, the gain in separation speed that sub-2 mu m particle columns might have over maximally performing 2.5 mu m particle columns is very small. Sub-2 mu m particle columns can only yield a gain in separation speed in the range of high-speed/low-resolution-separations (total time based on k = 10 below 5 or 10min). And even in this range, the actual gain that can be expected is only marginally small (only a few %). The present study hence suggests that the development and the use of particles in the 2-3 mu m range should deserve more attention than it did in the past few years. However, to be competitive, this 2-3 mu m material should be packed in relatively long columns, with a packing quality matching that of the current best performing 3.5 mu m particle columns. The supra-2 mu m particles should also be able to withstand the same pressures as the sub-2 mu m particle material one is comparing it to.