I've moved this thread to Script Request. Please be sure to post your threads in the correct forum next time. Thank you.
Javascript Plugin Support is for RMMV, not RMVXA, because Ace uses RGSS3, not Javascript.
That said, you won't like the answer to your questions...
There are different causes for lags, and most antilag scripts only reduce the lag caused by events moving or animating on the map. And they do that by stopping those events.
So multiple antilag scripts would not only not help, you'll also run the risc of incompatibilities which might make the game with several anti-lag slower than the game without any anti-lag.
Additionally, an ABS battlesystem needs more processing on the map than anything else - and unless that processing allows for special handling, no antilag will ever be able to help against that source of lag.
Given all that - if you had taken the time to read around the forum looking for older topics on map sizes, you would have found that it is usually a bad idea to make large maps not only due to lag, but also because large maps are impossible to fill.
How much worktime do you expect to put into that map? Under the condition that you are an experienced mapper, you'll still have to put in about a hundred working hours (my estimate) simply to make that map, without any events.
Do you have made smaller maps in RM in the past? If this is your first project I really doubt that you'll finish such a project.