There's nothing to worry about. It appears that AE uses more of the available RAM when using the Audio Sprectrum effect.
It's a fairly rare thing when ANYONE gets to RAM preview an entire AE comp. You only have so much memory. The same is true for almost everyone else. It has been like this for AE users since the very beginning. Nothing is wrong, and it won't do any good to complain about it. We all get used to it. You will, too.
You simply need to use the Work Area to preview select portions of the comp:
There are other tricks to get a longer preview. You should find them here:
There is a lot to read.
As Dave said, it very much works as it should - the plug-in loads your audio file to analyze it which adds an extra slice of memory used.
im using a imac 27 high spec i av 12 gb assigned for affter effects in my humbel opinion i dont think that it is coz i dont have enougf memory i av all the video copilots plugins i havent had any problem like this plz further advise thank you Dave, thank you Mylenium
Yeah, well, I have 24 gigs on my machine, and I can't do a full-resolution RAM Preview of a 720P comp that's any longer than 45-55 seconds.
I said it once, and I'll say it again. There's nothing wrong with your machine. There apparently isn't anything wrong with AE, either. You have to get used to the way AE works.