sorry, my understanding, when you wrote:
"the form in the "small frame" is done in a more "energetic" level, with small and fast movements."
I misunderstood how you were using the term "energetic". It seems more in line with the conventional (i.e., non-tcc) usage of the term.
As I would then understand it, the large frame could be done as energetically (i.e., with fajin, as Bamenwubu suggested). Other practitioners use "energetic" in a differnt sense.
When you write:
"The large/slow frame is not less energetic but is designed for the beginners (in my opinion up to 15-20 yearsof practice)."
It makes sense, and it's pretty well known that most of the jumps and kicks and "energetic" (if that's the right sense) parts were removed from the form.
(Yes, many schools still retain forms with these features. However, consider the Chen styles where there are kicks from handstands, etc. It could be argued, then, for ex., that Pao Chui is more energetic.
Yet, I don't think students are expected to wait for 10-20 years. This brings up what may be the fundamental distinctions between the Chen and Yang lineages. At least, it might be considered a point where they diverge in terms of their training, if not the desired end result --which is more important, imv.
In brief, I understand (hopefully) the idea that a more vigourous, physically demanding form is more energetic. And, that the large, slow form is less vigourous than others. I am not convinced that the small, fast forms require or cultivate the type of "energy" that people like YCF called chin or jin.
Btw, I don't claim to be able to define "jin." I'm only saying that the distinction is made between it and other types of energy.
I do agree that, after long practice of the long, slow form, one is able to express that "energy" is a small, fast way or any way one desires. It might even be acceptable to say that the small, fast forms are more oriented toward the application of whatever energy is developed.
"All will come at the right time. Continue to practice, there are no secrets/shortcuts
Oh, it's too late for me now. But, if I could master myself enough to be ok in the slow long form, I'd be happier than learning another form, anyway.