I assume you are talking about a MTB tire? Slime is heavy. My SO has slime in his tires, he got it put in for a ride in very thorny country. We were out riding and got into some fishing line. When he turned the bike over to work on getting the line out of the crank, we found he had a huge roofing nail in his tire. The slime had sealed around it. So it works, but it is heavy.
I run tubeless on my MTB....Stan's. I have not had a flat since.