Last time I went through the profiling tool in WebKit (I'm a Safari guy) I tackled any memory leaks. It's possible that some came back, since a lot has changed since then. I'll take a look at it as time allows. I use the site everyday myself, and I haven't noticed any sluggishness, especially as I've kept the site open all day. It helps to refresh occasionally, if only for the fact that I deploy 4-6 times daily, oftentimes with a small tweak or two, and sometimes with a large new front-end feature.
I love the service itself, but it brings my computer to its knees. Maybe the problem's on my end but sometimes if I use NewsBlur and click on 'Everything' everything grinds to a halt and I have to reboot my computer using a hard reset. I think it's a Chrome problem.