My results for this test:

Computer: Windows 10, 6 cores
SH3D: v5.2 b1 with 3.6 GB allocated
Plug-in: Advanced settings for photo rendering v1.3

Default settings: Q4 (including 1/2 AA, blackman-harris)

Variable settings: sampler
bucket: +/- 7 seconds (= default settings for plug-in)
fast : less than 1 sec
ipr: less than 1 sec
multipass: not available (where did you get that?)

Additional tests
global illumination: default, diffused bounces: 1 --> +/- 7 seconds (= default settings for plug-in)
gi: path, db: 1 --> 2:58 min (worst result of these 3 tests)
gi: path, db: 2 --> 6:20 min (best result of these 3 tests)

H