Hi, I share the same experience of ultra slow Dell G5 5590 when running on battery. As far as I searched there is no DELL provided solution and I am trully dissapointed. After a bit of searching and checking stats with Intel Xtreme Tuning utililty I found out that max TDP for CPU on battery is 15W while on charge it is 45W(with boost it is even higher). Another important stats that I looked at is "Current/EDP Limit Throtling" which is constantly enabled while running on battery. Last but not least, I have not seen any "thermal throtling" when I was running benchmarks while having Dell G5 5590 on battery. I also spot that CPU frequency is capped on 1.6GHz when all cores are running but it get higher with lower count of cores active. I spot on some forums that people were able to get a bit more perfomance when they disabled the dedicated GPU which actully lead me to think that the bottleneck is not thermal one but power related. Simply said the build-in battery is not capable to provide enough power to keep CPU on higher frequencies (probably to reduce risk of battery overheating). My solution will be to rise complaint as I have not found out any information on how severe is the perfomance degradation on battery for this notebook in the manual and request refund.            
I have a problem with my G5 5590 performance where it took a huge dip when I use the battery to run games and 3d modelling. I can tell that my laptop is capped at running at 2.2GHz at the most when running on battery and I'd like to know if dell ever consider to enable turbo boost on battery + adding custom TDP limit for the laptop when its running on battery (turbo boost is already enabled on bios). My daily experience when using this laptop extremely sluggish compared to my macbook pro 13 early 2013. I have reinstalled the entire os through dell recovery software to get alienware command centre to work and increasing the idle fan speed to 40%. (When alienware command centre is app is minimized the laptop's fan always kicks in on sleep and stopped constantly) This laptop only starting to feel faster on battery when I reduce the amount of active cores to strictly 2. The only reason I bought this laptop is due to its dedicated video card and.... the dedicated card is limited to 300MHz core clock when running on battery. I might have made a big mistake when picking dell for my windows machine, i find it funny that my 7700k is running faster and its only 4c/8t.  Imagine when you're in the middle of a conference call trying to show your 3D model work to your boss and forgot to bring a plug with you and in the conference the laptop lags so much when demonstrating it. I paid the full amount for the laptop and only receive half performance for the laptop. Are you joking dell? I bet if i purchase a set of memory module with 3200Mhz dell will only cap the memory speed at 2400MHz and it's not XMP configurable Specs: i7 8570H 6c/12t (runs like a dual core on battery) 16GB DDR4 2666MHz cl19 (constant speed very nice) RTX 2060 6GB (runs slow on battery Capped at 300MHz) Fan profile is terrible no consistency on stock (I don't want to replace my thermal paste every month due to the terrible fan profile dell) Just a thought on this laptop. And I don't really expect dell to embed any performance bios updates on their future release as most of them are just security and bug fixes. Having the laptop secure is good but what's the point of having it secure when it's not practical to be used on battery? I bought a laptop so it can be used when i'm outside using it without any plug if it needed to be charged all the time  what's the point? I can use my desktop instead.  I know this is problem arise strictly from the BIOS design dell implemented I have tried to remove drivers that may be causing the perf drop on device manager but the issue still persists.
Dell G5 5590 performance drop on battery