The past few weeks it's been laggy. Sometimes it lags and misses a stroke. This means I have to write each kanji slower, and I can't keep up now with the review. Slowly I've been falling behind and now I owe about 100 kanji.
:(

iOS or web app?

Web app. I'm using the same computer and same tablet as I have been for a year and a half. Would it be crazy to say it seems to have gotten better since last night? Maybe it was on my end.
It's still a bit laggy, but it did seem better this time.

That's probably related to some performance issues local to your computer, possibly caused by a browser, OS, or Flash plugin update. You could try making sure there aren't any other programs hogging the CPU, or you could try different browsers to see which is the fastest right now. (They tend to get slower and faster randomly with each update.)

"They tend to get slower and faster randomly with each update."
The browsers do? Or skritter?
It used to run fine, i'm using the same computer, and the same browser. I don't think I've updated firefox at all recently, but sometimes it's hard to tell.

Ok, I just tried out Chrome.
It seemed to lag differently, it would recognize all of my strokes, but was really sluggish and delayed.
It's better than it missing my strokes, but I miss when I could go full speed and get a large review done.
Thanks for the help though, for now this works.

I just want to add that I also get a little lag while using Firefox on my laptop, but it runs top notch on Internet Explorer 10. Chrome sits between the two of them when it comes to using Skritter.

So I might suggest you try changing to Internet Explorer and see if that helps.

Ok cool, I'll give it a shot thanks!

Yeah internet explorer works great.
I even finished my review a few minutes faster than usual. Thanks for that!

Glad that solved your problem. :)