In the client a special archive mechanism will be implemented, which will unpack and pack resources depending on the current battle. This can also result in freezes.
I sense this archiver mechanism is an experiment in the WoWS client, however it could also be implemented in WoT to prevent usage of certain mods.
The question is why this is being tested in WoWS and not, for example, in WoWP.
Notice: this feature could or could not be implemented, a decision from higher levels in WG is to be awaited.