I broke down the screenshot apps into 3 test categories:
1. Those that can save a screenshot directly to a file (bypassing an editor or dialog)
2. Those that save screenshots using the "save as" method
3. Those that can save in both modes.
There is a another category, saving to clipboard directly and independently, which wasn't tested. Only about 1/3 of the screenshot programs have this capability and they are all in the 3rd category. There is another possible category, uploading files, which also wasn't tested. I did however, identify the screenshot apps that included an editor and/or independent save to clipboard capabilities on the data spreadsheet.
These apps were time-consuming to test because of the configuration settings that needed to be constantly changed, which is one reason the tests were limited to 3 categories.
There were some issues that were discovered too. For instance, ShareX's RAM usage tended to creep up after each screenshot, where for most of the other apps the RAM in-use actually decreases. That could be because it's using some RAM for further future processing, and that could be corrected with a configuration change. However, some of these apps have so many features that a guide-book could be created on how to tweak them for the best performance for various specific use situations.
As typical, the top performing apps are those with the most limited features, but a few feature-rich screenshot apps are not far behind. It should be noted that the most versatile screenshot apps are those in category 3. That category includes WinSnap, FastStoneCapture, MWSnap, HyperDesktop (yaP), IrfanView, and Lightscreen. The data shows that these 6 apps are very similar in performance and although Lightscreen places last in that set, it's because its floating menu screen eats up 30MB of RAM in the benchmark rankings, otherwise it would be slightly ahead of FaststoneCapture. WinSnap, by contrast, also has a floating menu, but it only uses 3MB total for that window in the benchmarks. Both WinSnap's and Lightscreen's menu windows can be minimized to optimize performance. In any case, most of the differences between the six are only a few MB. If looking at in-use RAM only, FaststoneCapture uses less by far.
The more advanced and feature-rich screenshot apps use the most resources and that could be an issue on older PCs or in multi-tasking situations.
I only included a few charts, so see the spreadsheet for additional ones on the chart sheet. The spreadsheet data was uploaded to the link below with some select charts included below:http://s000.tinyupload.com/index.php?file_id=07109851442381527657