I hadn't noticed any interactive slowdown, but when I got around to running the notmuch performance suite, there seems to be some noticable slowdown with the glass backend (default in Xapian 1.3.5) compared to chert (using xapian 1.2.22) These tests are on an older i7 with 12G of RAM and an SSD. I'm reasonable confident they are CPU bound. One curious thing is the increase in system time in the glass case. It also looks like the glass backend is doing a lot more I/O, which could be related. The current notmuch performance corpus has about 200k documents, totalling about 3.5G. Unfortunately each number here represents only a single run. I did rerun the tests with the glass backend, and the variation was reasonably small. Chert ===== T00-new.sh: Testing notmuch new [0.4 large] Wall(s) Usr(s) Sys(s) Res(K) In/Out(512B) Initial notmuch new 669.06 639.78 21.42 323684 3576/9360440 notmuch new #2 0.46 0.00 0.00 8240 3568/200 notmuch new #3 0.01 0.00 0.00 7916 0/8 notmuch new #4 0.01 0.01 0.00 8008 0/8 notmuch new #5 0.01 0.00 0.00 8040 0/8 notmuch new #6 0.01 0.00 0.00 8040 0/8 T01-dump-restore.sh: Testing dump and restore [0.4 large] Wall(s) Usr(s) Sys(s) Res(K) In/Out(512B) load nmbug tags 5.85 2.64 0.10 11280 1376/40496 dump * 7.45 6.51 0.94 25272 104/27928 restore * 7.55 7.15 0.39 8180 0/0 T02-tag.sh: Testing tagging [0.4 large] Wall(s) Usr(s) Sys(s) Res(K) In/Out(512B) tag * +new_tag 200.13 183.01 7.08 38628 264/1664552 tag * +existing_tag 0.00 0.00 0.00 8356 0/0 tag * -existing_tag 153.47 145.00 4.02 34928 0/1626320 tag * -missing_tag 0.00 0.00 0.00 8252 0/0 Glass ===== T00-new.sh: Testing notmuch new [0.4 large] Wall(s) Usr(s) Sys(s) Res(K) In/Out(512B) Initial notmuch new 949.53 697.05 206.98 277436 1290744/21767856 notmuch new #2 2.12 0.01 0.02 8204 2552/160 notmuch new #3 0.01 0.00 0.00 8216 0/8 notmuch new #4 0.01 0.00 0.00 8192 0/8 notmuch new #5 0.01 0.00 0.00 8216 0/8 notmuch new #6 0.01 0.00 0.00 8144 0/8 T01-dump-restore.sh: Testing dump and restore [0.4 large] Wall(s) Usr(s) Sys(s) Res(K) In/Out(512B) load nmbug tags 10.78 4.06 3.59 11376 600/39832 dump * 7.44 6.52 0.91 25296 0/27928 restore * 7.74 7.24 0.48 8740 0/0 T02-tag.sh: Testing tagging [0.4 large] Wall(s) Usr(s) Sys(s) Res(K) In/Out(512B) tag * +new_tag 481.78 278.80 196.89 39448 0/1897360 tag * +existing_tag 0.00 0.00 0.00 8496 0/0 tag * -existing_tag 449.58 242.65 202.74 35456 0/2073520 tag * -missing_tag 0.00 0.00 0.00 8440 0/0