Memory Leak in Nim v2.x with Mummy Webserver (Reopen #22510)
### Description

I'd like to suggest reopening issue [#22510](https://github.com/nim-lang/Nim/issues/22510) by @guzba, as the memory leak problem persists in Nim v2.x when using Mummy as a webserver.

I am running a web server using Mummy, compiled with both Nim v1.6.18 and v1.6.20. In these versions, memory usage remains steady over days and weeks, even during peak loads. After high-memory usage periods, the memory is efficiently released, and caching works as expected.

However, when compiling the same codebase with Nim v2.x (currently tested on v2.2.0 and v2.2.2), memory consumption skyrockets rapidly and never decreases. The memory is never returned to the system, ultimately leading to an **OOM crash**.


### Debugging & Investigation

* I have thoroughly analyzed my code using Valgrind to eliminate all directly and indirectly lost memory allocations.
* A significant memory leak from `parseJson` on invalid strings was identified and resolved in [PR #24686](https://github.com/nim-lang/Nim/pull/24686), but the overall memory leak issue remains. I also patch my Nim v2.x install with this bugfix, but it is no different.
* For my full scale test I have only tested with `--mm:orc`.
* I’m using Mummy but in combination with managed threads and channels.
* The only difference between my two environments is the Nim version. My code and all dependencies (managed with `nimbledeps`) remain unchanged.


### Evidence

I have attached a **12-hour memory usage comparison**:
* Left side: Nim v2.2.2 (memory usage continuously increases).
* Right side: Nim v1.6.20 (memory stabilizes and behaves correctly).

![Image](https://github.com/user-attachments/assets/4e056206-42ab-4416-9279-9d52db9665cf)



### Expected Behavior

Memory usage should stabilize over time and return unused memory to the system instead of growing indefinitely.

### Nim Version

Working versions
* 1.6.18
* 1.6.20

Non working versions
* 2.2.0
* 2.2.2

According to previous issue#22510 problem also persists with v2.0.0.
