When I do projectile-find-file I can see several messages:

Tramp: Inserting /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile'... Tramp: Encoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile...done Tramp: Decoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile with function base64-decode-region... Wrote /var/folders/mk/l2wm04594f1_106sn9lj4kd80000gp/T/tramp.436SVy Tramp: Decoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile with function base64-decode-region...done Tramp: Inserting/ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile'...done
Tramp: Inserting /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile'... Tramp: Encoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile...done Tramp: Decoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile with function base64-decode-region... Wrote /var/folders/mk/l2wm04594f1_106sn9lj4kd80000gp/T/tramp.436EfB Tramp: Decoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile with function base64-decode-region...done Tramp: Inserting/ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile'...done
Tramp: Inserting /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile'... Tramp: Encoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile...done Tramp: Decoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile with function base64-decode-region... Wrote /var/folders/mk/l2wm04594f1_106sn9lj4kd80000gp/T/tramp.436RpH Tramp: Decoding remote file /ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile with function base64-decode-region...done Tramp: Inserting/ssh:192.168.13.205:/home/mico/src/fdl/localStorage/.projectile'...done

Don't know if this is slow because there are some repeatings but tramp itself is ok, e.g. rgrep works fast.