Does My '10 MBP Suck?

So, I'll be brief.

I bought a 2010 15" MBP 2.4Ghz i5 with 8GB RAM back in 2010, I forget what the gfx card is but it has 256mb of RAM. To preface, I occasionally build PC computers for gaming and 3d work, so I am very familiar with computers and their components.

I am a web & mobile designer and work fulltime at my company's office, so I never really used my MBP for much work other than web browsing, blogging, photo editing, some basic work, not much photoshop...(I did make a photo slideshow but that's a different story).

Now that I am doing some mobile (iOS, retina graphics) work & building my wedding website, my MBP is having a HARD time working on these tasks. I am actually really surprised at the poor performance I am having. As an example:

My wedding website is about 1000x6000 pixels and is only about 50-100ish layers, mostly shapes and text. Really not a complicated file at all. Its so vertical because its a scrolling site. My MBP is chugging when working in Photoshop on it. Very laggy when scrolling, moving, or transforming objects. I dont have a ton of running simoultaneously...browser, itunes, bridge, not much else. Working on retina graphics is also pretty difficult.

In the past I was always doing my freelance on my PC, and NEVER had any problems (though it was very powerful). My concern is, while I was originally wanting the new iMacs that are supposed to be announced/released this year, is that going to be enough power? I worry I may need a Mac Pro. Do I have a bad laptop? I should mention I bought with the hi-res display, but it is in clamshell hooked up to a 21.4" 1080p external monitor.

I was wondering if others have similar performance? I see many designers who do a lot of work on their MBPs, do they just endure this poor performance or am I unlucky? What's going on? It handles all non design related tasks incredibly well. Is this a compatibility issue with Lion?

Thanks everyone, would love some insight.