Can you try running the proper DOOM benchmark timedemo to get accurate results? It plays through a level of the game and results with some numbers which will give you an average framerate. It's how we compared DoomAttack and ADoom to find out that DoomAttack is faster, but you need to be able to run the game from CLI to add the extra arguments, which I'm not sure if BOOM on the Amiga supports.
Here's the page about the DOOM Benchmark: http://www.complang.tuwien.ac.at/misc/doombench.html
I'll add a quick report about our experiences with Amiga BOOM so far, in case NovaCoder wants any feedback.
Earlier BOOM worked on the A1200 with a 128MB DKB Mongoose 030@50Mhz and an A1200 with a 64MB Individual Computers ACA1230@56Mhz, but failed to run on the A1200 with DKB 1202 with 8MB RAM or an A1200 with a 64MB DKB Cobra 030@28Mhz. A few weeks later a new version was tested and works on the DKB Cobra too, but we could never figure out why the older version didn't work.
We tested No Rest for the Living too, which ran really well in DoomAttack. Very nice level design, thanks XDelusion for digging that one up for us.