Is 256 gig same as 1 TB?

Of course, SSDs mean that most people have to make do with much less storage space. A laptop might come with a 128GB or 256GB SSD instead of a 1TB or 2TB hard drive. A 1TB hard drive stores eight times as much as a 128GB SSD, and four times as much as a 256GB SSD.

Of course that is a common knowledge but my question is, does laptop can go slower with more gig?

It won’t as long as it is designed for higher gig.