Performance difference in Nitrokey HSM2 key generation

Nitrokeys HSM
1

Hello,
I have two Nitrokey HSM2, but I’m consistently getting different performance times on the same operations.
In particular both of them slow down with the increase of the number of stored key pairs (RSA4096) in performing the following operations:
- Key deletion
- Certificate generation
- Certificate storing
- Signing
- Signature verification
but one of them is much slower than the other on these operations from the beginning, and the total time accumulates, becoming very impactful (about the same total time on performing the operations on the first key, double the cumulative time when generating and storing 5 key pairs).

Can anyone help me understand the cause of this discrepancy between the two Nitrokey?

2

What firmware version is this ?

When you frequently erase objects, then the Java garbage collection kicks in and reorganizes memory. That can take a couple of milliseconds. Also the 4.x version with JCOP4 is considerable faster than the 2.x and 3.x versions (JCOP2/JCOP3). JCOP4 used flash memory, while JCOP2 and JCOP3 use EEPROM cells.