Is it possible to get plugin's load duration, RAM usage, and usage statistic (if this plugin really used or not) per plugin on IntelliJ IDEA 14?
Most features of IntelliJ plugins are loaded on demand when the corresponding feature of the IDE is used (for example, extensions for the rename refactoring will only be loaded when you actually try to rename something). Because of that, there is no such thing as the load duration of a plugin.
As for the usage statistics, plugins can silently and transparently modify the operation of other features in the IDE, so it's also not clear what exactly the usage statistics of a plugin would mean.
RAM usage might theoretically be possible to track, but this is not currently supported.