How to prevent actors from not being loaded when you open a Level or map?

I have noticed that in a level I load on my game, If you have a powerful computer, it loads with no problems at all.

The thing is that on my old computer, its not just a question of time, also I can see that the first time I run the game and load the level or map, doesnt load everything I placed in there. When I say everything, Im talking about real important stuff on the game like plants which are the ones that makes you survive on the gameplay and are distribuited around the map. The old computer is not able to load the plants so players with old computers can not survive.

How can I prevent plants (actors) from not being loaded when you open a level or map?
When this happens, I got a TEXTURE STREAMING POOL error but even if I update it to 2000, I was still wondering how can I force plants to be loaded and spawned around even if you have a TEXTURE STREAMING POOL problem, somekind of critical loading things so yes or yes will be loaded?

Thank you.