Firebird 5 performance (I/O?) issue

[EPluribusUnum]

Hi *!

We have a test envionment: VM machine, Win11, 8G RAM.
The test program is a Java8 app (Jaybird 5.0.11). It executes around ~200K SQL commands on ~ 10K transaction during the whole run.
Here are the results of different FB engines runs.
FB50 is much slower than 40 and 30, even when the system memory doubled.
FB50 has a huge I/O compared to 40 and 30. This might be the cause of the speed difference.

I can send you the testing environment on request.

Thank you!

3.0.13 SuperClassic, x64

Script (test) time: 1 min 40 sec 408 ms
Init (iter) time: 8 sec 903 ms
Script (iter) time: 17 min 22 sec 661 ms
Test time: 21 min 29 sec 887 ms
Cleanup time: 3 min 7 sec 569 ms
SQL Operations time: 37 min 19 sec 569 ms
Complete run time: 42 min 7 sec 493 ms

4.0.6 SuperClassic, x64

Script (test) time: 1 min 45 sec 920 ms
Init (iter) time: 8 sec 427 ms
Script (iter) time: 23 min 28 sec 877 ms
Test time: 27 min 26 sec 775 ms
Cleanup time: 3 min 40 sec 705 ms
Total time: 1 hour 4 min 39 sec 624 ms
SQL Operations time: 48 min 32 sec 901 ms
Complete run time: 50 min 49 sec 989 ms

5.0.4.1776 SuperClassic, x64 (also tested with 5.0.3, 5.0.2 and 5.0.1 with similar results)

Script (test) time: 11 min 35 sec 895 ms
Init (iter) time: 5 min 48 sec 466 ms (prepare included)
Script (iter) time: 1 hour 35 min 6 sec 75 ms
Test time: 48 min 22 sec 636 ms
Cleanup time: 5 min 13 sec 153 ms
Total time: 3 hour 6 min 11 sec 7 ms
SQL Operations time: 2 hour 6 min 8 sec 451 ms
Complete run time: 2 hour 29 min 11 sec 789 ms

same as 5.0.4.1776 but with 16G RAM

Script (test) time: 9 min 47 sec 137 ms
Init (iter) time: 3 min 23 sec 644 ms (prepare included)
Script (iter) time: 1 hour 15 min 31 sec 198 ms
Test time: 34 min 17 sec 743 ms
Cleanup time: 4 min 33 sec 172 ms
Total time: 2 hour 26 min 5 sec 695 ms
SQL Operations time: 1 hour 30 min 55 sec 885 ms
Complete run time: 1 hour 58 min 3 sec 239 ms