While precise evidence is difficult to gather remotely, one or more scripts frequently "hang" SWB -- not just when attempting to use the application but even just attempting to "look" at someone's plot data. The above screen-clip (Firefox debugger window) is just one example but anecdotal evidence over time (since the last SWB major "makeover") suggests the difficulty might be with "outside" scripts/widgets associated with "external" links with "unrelated tools and services"; i.e. with the likes of Facebook, Twitter, etc.
IF (bold intended) this were actually the "root cause" (or even A root cause) , then I'd suggest complete removal of such linkages as unnecessary interference with what, otherwise, was intended(??) to be a scientific application (right???). Links to "social media" probably do have benefits to other aspects of PLab, but I do question this specific linkage type to a measurement tool. [ On thinking about it, I'd still recommend removal of any and all "extraneous" linkages/tools/widgets/etc from the SWB interface page(s).]
Preface: I do not write this to complain but only to propose a new perspective; I do have other means of making spectral measurements and doing custom processing but the issues with SWB do make observing that data more difficult.
Yes, I will also admit that my experience with poor to zero performance with SWB may be worse than average, performance is likely related to distance to server and network traffic, and it is generally true that these types of issues will fall into some "bell curve" of user experiences. However, it is also a common characteristic that when a tool fails, a very small fraction of users will report it. The corollary is, therefore, that such an issue is generally much more significant than indicated by the # of times it is reported.
Because SWB is, in theory, a scientific, "cloud-based" measurement application, a primary criteria should be clutter-free intuitive efficiency and, therefore, the user interface should be optimized with that perspective in mind. IMHO, the most recent incarnation of SWB diverged completely from such a goal; despite/including the addition of new features. [ My guess is that much of this may be related only to the UI layer, not necessarily the underlying engines, which might make the solutions more tractable.]
I hope these observations are helpful.
Cheers,
Dave