ARM processors have, so far, been targeted to mobile, low-power applications for a very long time. When it was launched, powering a desktop computer (the Acorn Archimedes), its speed was comparable to then current 386s with FPUs.
There is nothing that prevents building an ARM processor that performs as well as a current x86. In fact, due to its simpler implementation logic, an ARM implemented with the same technology as a x86 would probably run faster or leave more silicon for caches, inter-core communication, more cores and specialized logic.
There is nothing that prevents building an ARM processor that performs as well as a current x86. In fact, due to its simpler implementation logic, an ARM implemented with the same technology as a x86 would probably run faster or leave more silicon for caches, inter-core communication, more cores and specialized logic.