I see evidence of this in several BTMs that I use often. Below is a simplification of it. This is a very recent development in v24 on Win7/32. I have run this test and similar ones many times; the results are always similar (v23 about 30 times faster than v24).
v:\> type slow.btm timer do i=1 to 100 echo > nul enddo timer v:\> ver & slow.btm TCC 24.01.41 Windows 7 [Version 6.1.7601] Timer 1 on: 16:19:33 Timer 1 off: 16:19:34 Elapsed: 0:00:00.92 v:\> g:\tc23\tcc /c ver ^& slow.btm TCC 23.00.34 Windows 7 [Version 6.1.7601] Timer 1 on: 16:19:43 Timer 1 off: 16:19:43 Elapsed: 0:00:00.03