CURRENT: why is CURRENT swapping so fast?

I use my boxes for daily work and in most cases, the usage of applications is the same.
Compiling the OS and updating ports while having claws-mail and firefox opened is some
usual scenario.

I realise since a couple of weeks, if not months now, but always sticky to 11.0-CURRENT,
that the system is even with 8 GB RAM very quickly out of memory and swapping. As of
today - updating CURRENT (buildword) and also updating ports. Nothing else except
firefox. And the box is using 1% swapspace.

It is hard to reproduce or give exact numbers or any more scientific values. But the way
I do my work is monotonic and it is more than obvious that the box is swapping much
faster right now than, say, 6 months ago. The problem occurs on different hardware types,
one box has 8 GB, the other 32GB.

There are some strange behaviours when compiling ports or the OS itself sometimes. I very
often linker errors with something like

[...] relocation truncated to fit: R_X86_64_PC32 [...]

This strange behaviour sometimes occurs immediately I switched on the box and start
updating and building world (nothing else done so far) or updating a port. When this
error occurs, I reboot and do the very same job again - and then suddenly it works. It
seems I can not reproduce this problem either. It occurs on 11.0-CURRENT since a couple
of weeks by now and affects different hardware types (as with the unspecific swapping
experience mentioned above, either 8GB and 32GB, but it occurs on the 8GB bixes much more
often than on the 32GB system).

I'm sorry about this unspecific reporting, but since I observe this strange behaviour but
can not successfully reproduce it by will I suspect something "faulty". I did already RAM
checks on the systems affected - without any abnormal occurence of memory faults or so.

Regards,
oh