bug#21453: 25.0.50; When font size is temporarily increased Emacs is slow

[Mark Karpov]

Oh my! It seems I've spoiled the whole thing. I didn't notice that
`with-timer' takes TITLE argument. This leads to the form evaluated
twice. (I copied this snippet from one site.)

Let me know if you think it should be tested again. Although current
results demonstrate that slow-down is considerable and I doubt it won't
change if we evaluate the form only once.