I assume you mean cold snap and not Iceblock. In case you actually meant Iceblock. Personallly, I use both Iceblock + GInvis. Use Iceblock during the cast of Ionization for < 1 sec max downtime, then GInvis for the others.
Doing this, it equals more time standing in the initial pool with Time Warp up + pot/procs etc. pool.