SEVERE fps drops when generating scene? texture generation?

imported a pretty simple shed object into my scene so mess around in, but whenever i play the scene there’s a HUGE drop in fps for a few seconds, it eventually goes away but it’s pretty crippling for a few seconds.

is this due to it generating the textures on the shed? (they’re rather high res) and if so, how would i make it so those PRE generate instead of trying to pop in on every play?

What resolution are the textures?