Self Propelled 10515 Hard to Push

Are Self Propelled 10515 Hard to Push compared to a Push Mower?

I just got this and it was hard to push around trees compared to my just push..

Its not all that much harder but it doesn't roll as free..

I thought I found the issue when I was pushing in 1st but same thing neutral..

Can it be I need to lube trans?
I did grease axel need back of wheels...

Thanks...