Often depends on the workload. My work requires compiling the kernel regularly (among other things) and 5 minutes saved over 12 compilations in one day is an entire hour saved. Made up numbers, and in the case of a lot of other code I touch it makes even more of a difference. On the other hand, I ssh into a work desktop from a work laptop, so a Chromebook with an SSD would probably still be useful if I could get over the lost screen real estate and low quality keyboards