The game doesn't display your IGT for the first paperclip, first time message is at 500 clips and 5 funds. So there is no way to measure IGT that way.
The letter of the rules also state that your IGT is what is displayed at the end so it is a contradiction if you will.
Although the rules does say that time start with first paperclip the relevant time is IGT which start when you load the game so it doesn't help.
You can't use an autoclicker. IGT is displayed at the top when the run finish it should always be lower than the RTA time (usually quite substantially lower). You can use livesplit and obs for recording and timing.
How did you measure your RTA time?
The backspace on execution is very early but I believe it is still late enough to be valid.
As we can see in the new run a significantly worse run beat out the previous run by the same person because of the fact that it is ranked by IGT that is not currently working. marcf99 old run was a 1:38:27 real time while the new run is a 1:43:58 so 5 minutes worse.
Using IGT as previously mentioned give a gigantic advantage when it comes to yomi and stocks since both of those are on a separate timer which make any extra real time practically free time save.
It isn't really normally about lag it is just about how often the browser runs the main loop. For me firefox is 5% to 10% slower when measured so you probably need to use chrome.
If you have a slow enough computer it will start to run the main loop less because of lag but I would guess that for most it is just about browser.
IGT is not accurate for this game, stocks and a few other things are on a separate timer and will be relatively faster on slower computers compared to IGT.
During patch 0 you could buy strategic attachment while only having 1 strategy unlocked and generate yomi from always winning very quickly. This is not possible in current patch.