World leaking memory.

[Kuba0040]

Hello.
Over the past 2 years I have been trying to fix a problem with one of my oldest tekkit worlds from 2013, on which I played regularly till 2017 
 

How it broke:
In 2017 the world was used a server which was hosted by aternos.org, one time the server crashed and when I restarted it, only one chunk would load into the world, after 2 weeks of trying to fix it (I deleted the player position files and removed the broken chunk using mcedit), I brought the world back to life, however over the next month it started to leak memory. 

Current problems:

The world leaks memory (around 1MB/s), when you log into it it imidietly goes up to 5GB of Ram used and climbs up till it reaches the limit of 10GB, then it crashes. Ram usage never goes down, however when you press F3 while playing the world, minecraft shows that only 3GB of ram are used (the ram usage also is shown to decrease and increase normally by minecraft's F3 view).
The world also has a problem that is hard to explain so here is my best shot at it: Let's say  you want to open a chest, you click on it.... and nothing happends, and then suddenly after 10 seconds, the chest GUI opens, other times however ( In the same area of the world) you click the chest and it opens imidietly, this effects all blocks.
The last problem is the random lag spikes, they ususaly appear out of nowhere after 10 minutes of playing, and last about 5 seconds durring of which the world ram usage increases drasticly. 

If anyone who is more smarter than me knows whats wrong, let me know how to fix that issue, I should also say that I have daily backups o the world (while it was a server) since the server crashed.  Here is the link to the latest save with all the problems I described: https://drive.google.com/open?id=1DTD69nXBSOgbzVAPevAixXx9tGdx60US

Why don't I just load a backup?
The server developed at lightspeed, there are just so many great builds I would be very sad to lose.