Using eSpeak commandline 1.45.40, with the following command line:
espeak -s 300 -m -f test.txt
Where test.txt contains:
<mark name="1" /><voice xml:lang="en">1 2 3 4 5 </voice>
Espeak for me speaks this at a very slow rate. Yet if I remove the <mark name="1 /> from test.txt it speaks it at the correct speed.
I think it has something to do with a mark tag directly preceding a voice tag as NVDA has provided eSpeak mark tags in the past with no problems, but is only now also sending voice tags.
Note also that for NVDA at least, the rate continues to stay at the slow value even for future espeak_synthesize calls, and only gets corrected if the rate is manually changed with the API.
Fixed now in eSpeak 1.45.41 at:
http://espeak.sf.net/test/latest.html