ccache mount location questions

Hi,

1. The system is zfs there is no other storage.

2. ccache dir is in its usual location /var/cache/ccache

3. would it be advantageous in terms of speed to turn on
    compression here? I'm thinking lz4 but maybe other settings are
    preferable in the context. Muscle memory says leave compression off
    but i have read that compression can speed up access, which is why
    I'm asking for clarification. (asking here because it's the
    most likely froup building stuff)

ccache.conf has max_size = 25G and is ccache4. 
OS is stable/15 recent amd64 64GB RAM

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