The secure server connection can cause slow-downs - some suggestions here. The idea is to either disable DNS or give an IP the VM can see.
Disable DNS
Open a terminal
...
Search for UseDNS, uncomment and set to no:
UseDNS no
Example:
tic,[s,r] = cspm_sshlinux_sendcommand( 'echo $SUBJECTS_DIR' ),toc
20.7 seconds before, 0.6 seconds after.