+1

Servos are mechanical, varying quality of motors can only go so fast, some offer coreless, brushless, metal cases with bearings, etc... far too many variables which affect performance. In contrast, the "E" in ESC stands for "Electronic", nothing mechanical there to slow you down.... in fact most folks look for features to actually slow down their ESC, such as punch control, with stages or expo rates, etc.

While attending a race clinic last summer hosted by Ryan Lutz and Joe Bornhorst, they explained that having too fast of a servo can be detrimental as well (smoother is faster) and they recommend a servo somewhere in the 0.08 - 0.12 s/60° range. Watch that linked video and you'll get a better understanding of what the term "smoother" really means.