I would argue .5 seconds is longer than it actually takes. It's quick for me with 4 spaces. Not instantaneous, but I'd be hard pressed to feel like I was losing time to it.
But, perhaps with 9 spaces and most RAM utilized, it starts to chug. Definitely plausible.
Don't know if there is a way to disable the transition. And I don't understand the concept of "getting rid of the grid". Do you mean when you look at all spaces at once you want the spaces to be touching each other and not separated? Or layered? The grid seems to make sense for looking at all spaces at once. Nothing jumps to mind as being more efficient.
One thing to try that I set up is using key combinations to go directly to a space. I can pres ctrl and 1, 2, 3, or 4 and go directly to that space. That does save time of seeing all spaces and choosing the space from all available spaces. I lightly categorized the type of tasks for each space and set some apps to always open in a particular space. E.g- regular apps (Mail, Quicken, iTuens, etc.) open in Space 1, Space 2 is for my VM, Space 3 is for Remote Desktop connection, and Space 4 is for utilities (Activity Monitor, Disk Utility, Terminal, etc.).
Though, more often than not, I just Command-Tab through applications. I usually only have 5 to 10 open at a time, and since you can add Shift to the mix to go backwards, that's pretty quick, too.
Good luck with the hunt!