May be faster when you create a plug-in for this.
Doing this from a plugin will be MUCH faster and more efficient. The JS interface wasn’t designed for this.
Do you mean the Forms plugin included in the SDK of a custom plugin?
And the answer is NO, the forms plug-in is for handling form field data and properties, and you said you wanted to change annotation properties. In the JS world Annotation means a markup or drawing annotation. In a plug-in this has to be done with either the PDAnnot object methods, or through raw COS object properties.
Annotations have the nasty property of trying to redraw themselves if any property changes. This has always made updating annotations slow. So one option to speed up the script is to turn off redrawing with the "annot.delay" property. Set this first before making any updates. Then reset after all annot changes have been made. However, it won't ever be as fast as using a plug-in