Memory usage increases per page load
I'm porting my own site/app to Jester and after getting a substantial amount done, i noticed it was using ~800MB of ram. Investigating, i see that every request+response (page load) causes more ram to be used. At first, i noticed this due to the fact that i'm serving videos via html5 video on some pages, and the ram usage goes up quickly, evidently due to  #181. Prior to this, i was using httpbeast, but it couldn't serve the videos at all due to #241, so i switched to asynchttpserver. 
Now, to try and rule out my code, i'm just testing with a simple route 
```
routes:
  get "/":
    resp INDEX_HTML.format("")
```

and serving an html string 

```
const INDEX_HTML = """
  <html>                                                                                                                                                      
  <head>
  <meta name="title" content="ITwrx-Jester" />
  <link href="http://ITwrx-Jester/assets/css/ITwrx.css" rel="stylesheet">
  </head>
  <body>
  <h1>Responding with html from separate file with Jester.</h1>                                                                                                <body>                                                                                                                                                      
  <p>This is only a test. If this were a real paragraph, it would be much more interesting.</p>                                                               
  </body>                                                                                                                                                     
  </html>
  """
```

and it still uses more ram per page load, just much less than a video page.

Both httpbeast and asynchttpserver exhibit this behaviour, but it's more aggressive with asynchttpserver. I've tried nim 1.0.10,  1.2.8 and 1.4.0 and it happens with each. I'm using Jester 0.5.0 on fedora 32. I think it was happening with 0.4.3 too, IIRC. I'm currently running with:
`nim c -d:ssl -d:useStdlib -r ITwrxJester.nim`
ssl is needed for smtp in another route.

I tried debugging with the built in profiler and it successfully saved a text file once, but i can't interpret it. Also, that profiler report was from when i was surfing the whole site, not just the index page, if it matters. If you want a profile from just the simplified test, let me know.

https://pastebin.com/P3QX8FQc

I also got a report from valgrind, but i have no experience with that and it makes very little sense to me. Let me know if you want me to attach that, assuming it won't have sensitive info in it (i'm not sure what all is in a typical callgrind.out).

I'm still hoping i'm doing something wrong.

Thanks
