Lag

Have you optimized your options in the game? Like, disabling anti-aliasing and such?

 

Internet latency (lag) is easy to distinguish from low performance or stuttering on your machine. If things still animate smoothly but stop acting properly (i.e. characters stop and just do their idle animations instead of moving around) then that is a problem with your connection, as the game is no longer receiving instructions so it just goes to to the default animation.

Poor hardware performance on the other hand almost always results in a low framerate or stuttering (everything stops for a split second, and perhaps when it resumes it is as if that moment still happened but you didn't see it happening - it just wasn't displayed).

I'd say that it's probably mainly down to the GPU underperforming. Low framerate isn't going to be caused by insufficient RAM. Integrated GPUs aren't the best when it comes playing modern games.
However the drop in responsiveness after your close it does indicate a RAM issue, as it is probably swapping out system resources while you play to make room for the game, and then having to swap them back in after you are finished. If you have more RAM it would be able to keep everything and not have to wait and drop responsiveness afterwards while things are moved back.

As caramba said try dropping down all of the graphics options as low as possible to see if it makes any improvements. If it does, then you can try increasing them one by one until you find which one(s) have the most impact.

 

You need to upgrade your laptop in general.

RAM is great for memory intensive purposes (games, simulations, multitasking), but when it comes to game rendering, upgrading RAM will not see much improvement. A Dedicated graphics card and a decent CPU (2nd gen i5 MIN) are necessary to run games on a laptop.

If it is your latency, ie the number next to your skill bar, than that is a network problem. The only remedy to this is a better connection, whether it be changing from a wireless to a wired connection, changing the server you play Diablo on or upgrading the speed of your internet.

 

When I say "upgrade your laptop" I actually mean "get a new laptop".

The limitations of an Intel Graphics cripple most games and are added to laptops mainly for processing videos. Gaming will require a more intensive graphics card in general.

Lowering the settings in Diablo will see some improvement, but honestly you will be better off purchasing a brand new laptop. Fortunately for you Christmas is around the corner and laptop prices are really cheap. My current laptop that can actually run Diablo set me back about a $1000. It would now sell for about $300-$400 (and it's barely a year old).

 

Anti-aliasing is basically the process of making rough edges on images/figures/whatever smoother. So it just makes the whole game world look prettier. In Diablo, if you go into your options there's a tick-box or drop-down menu or something that lets you change how much it is.

Definitely change your graphics though. Fiddle with the options. My computer is pretty solid for gaming and I was having issues with Diablo as well... started by setting everything to the lowest possible to improve the framerate, then increasing little things here and there to improve the look of the game until you find a balance you can live with. If you start low and work up it'll seem nicer than starting high and working down, y'know?

I can't remember if there is a framerate display in Diablo, but it might be worth checking for that too.

Also, playing in windowed seems to run faster than playing fullscreen, and playing in 4:3 aspect seems to run faster than playing in a 16:9 aspect (from what I've found).

 

Frame rate checker is ctrl+r. It appears in the top right corner

Also windowed mode will tend to play games a little more smoother because the graphics card doesn't have to render at full resolution. Windowed Fullscreen is perhaps the worst setting you could put it on.

 

Not necessarily.. depends on how the process and GPU fit together in the graphics pipeline. Windowed mode can give the game more threads to work with as it gives the OS more control over the process. Windowed mode also typically makes the GPU disable some features that it only supports when in fullscreen mode.
Most of the time it will be worse than in fullscreen, but you really just have to try it to see.

 

I play Diablo 3 on my old 2009 Macbook Pro...with a NVIDIA GeForce 9400M 256 MB graphics card. Hooked up to a 23" monitor lol...but still squeezing out about 12~18FPS I'm horrible, but I'm making do with lower settings, but I'm used to the low performance by now.

But my settings are 1354x762 (16:9 widescreen). (this has a lot to do with performance as well)
No letterbox,
no vertical sync,
left the max foreground and max background as defaults.

Texture quality is HIGH.
No shadow quality
Low physics (I found this computationally expensive - frame rate drops like crazy when I change it any higher for me)
Clutter density OFF.

No anti-aliasing (my eyes T_T)
Low FX on.

There's apparently something else you can adjust as well in the settings that's not available in the in-game options GUI that can possibly improve framerate as well. Disable Trilinear Filtering which you will have to access this folder:

~/Library/Application Support/Blizzard/Diablo III/

and find D3Prefs.txt

then search for the line that says "DisableTrilinearFiltering"

and change the 0 to a 1. Save and quit.

Try loading up the game again .

(Also, I've played on my windows side as well, but I've found that the Mac OS side seems to run smoother ever since the second patch)

 

Today I learnt that people actually use Macs for gaming.

Crazy.

 

I've never played it but it looks like (Diablo III - Physics System Demonstration - YouTube) it comes into play quite often when you break stuff, and used to simulate cloth movements, and to animate enemies flopping around after you kill them. Lowering it probably makes the simulations progressively less accurate.