Temporary Tables on virtual memory

Hello everyone,

I’m running a configuration with one master and a replication slave. Both on Linux.

For better performance, I decided some days ago to put the tmpdir to /dev/shm like a recommandation I read. And the performance increases a lot. Because I’ve a lot of created_tmp_disk_tables created (about 751K on a total of 3743K of created_tmp_tables. Because on my SELECTs, I must get text fields).

But today, I read this :
http://dev.mysql.com/doc/refman/5.0/en/temporary-files.html where it was specified to don’t put the tmpdir to virtual memory on a slave.

So my question is : In which case, it is dangerous to put the tmdir in virtual memory for a slave ?
Do you have a workaround to continue to put only created_tmp_disk_tables on virtual memory and not the temporary tables necessary for the replication ?

Thanks for yours answers.

Best regards.