Odd Memory Usage #1135

Hi!

I've been using this library for a while and noticed an unusual behavior regarding memory usage. When my consumer receives a lot of messages, the Node.js application's memory usage naturally increases. However, I've observed that while heap usage decreases after processing the messages, the .rss (resident set size) memory remains significantly higher than expected.

Here is an example of what I'm experiencing:

• Initial Memory Usage:
  RSS: 200 MB
  Heap: 50 MB
• During Message Processing:
  RSS: 1.5 GB
  Heap: 500 MB
• After Processing:
  RSS: 1 GB
  Heap: 60 MB

Is this the expected behaviour?

Thanks!