It doesn't matter how much phone hardware you throw at this game. The game is simply poorly optimized. I have a 5600X at 4.5GHz and 64GB of DDR4-3200 running on an NVME SSD and even it struggles because the problem is not one that can be solved by better hardware.
This is due to a huge variety of issues with her "practice / methods"
1.) Storing all the Dialogue in Strings rather than a text file (which also makes translation nigh-impossible)
2.) Re-initializing many things that don't need to be, including some strings being initialized multiple times because they're stored in a reused class. Those strings could just be static and improve performance 3-8%
3.) Lack of Threading for tasks that could easily be threaded (Daily / Hourly NPC updates), Loading NPCs, Saving/Loading
4.) A poor grip on base functionality of java causing her to make variables called "javaMadeMeDoThisExcuse" to work around a simple misuse of object. ETC...
That's why with just a IntelliJ IDEA Function of "Optimize Code" which deals with simple issues for you, gave +15-20% performance alone. Among other small scale changes I made her code perform quite a bit better.
The rewrite branch of the project managed nearly 200% performance gains and a 50% cut in memory usage. However it was a pain to maintain (updating LT's latest code and fixing it) so I dropped it.
If Innoxia let me I could get it to compile 5x faster, run 2x better, with half or less memory footprint in 1 big commit. Or several smaller area specific commits, but she practically refuses assistance.
Edit : I have talked to her in DMs about this, she's not too keen on someone else taking a rake to her code.
She seems content on just blaming Java itself, rather than blaming her lack of Java understanding. There is a reason Java is used in high end projects like Chemistry software, it's really good at managing data.