Huge JAR that Android Studio (more precisely, dx) takes a very long time to convert to DEX?

Question

Java

There is one library.
It has two versions - .NET and Java. I'm actually interested in the second one. It is called Java, there is no talk about Android, but I asked the developers, and they said that it was compatible.
Only now the library weighs about 5 MB, and there are 1387 classes in it (I unpacked the JAR and counted).
Therefore, when I tried to add it to Android Studio and build the project, it took a very long time, it's already 1.5 hours, and everything is building.
I tried manually through dx, even opened it in Eclipse on an old computer - the same story, everything flies with others, but you won’t wait for this one.
What can be done?
It is not in the repositories, it is commercial.
Do not offer analogues - I'm used to it, and there is already a lot of code on it.
It is somehow inconvenient for the developers of the library to write - I have not bought it yet, I only plan to.
I think it is necessary to somehow "prepare" DEX once and for all, so that later it can be freely transferred from project to project along with JAR.
But how?
I know about MultiDex, but the IDE itself needs a JAR to see the classes, I don't want to work through reflection :)