Frame rate is significantly lower than previous versions

do you have setting other than Unlimited for FPS limit option and how many chunks do you have set to render

Also, what are your system specs?

(don't see a reply function so I'll answer in here and hope you see the comment)
Dawid: I have chunk rendering set to 24 chunks, do you just need my video settings in general? if so I'll say more if needed
Violine: Hope this is what you were asking for.

OS Name Microsoft Windows 10 HomeOS Name Microsoft Windows 10 Home
Version 10.0.17763 Build 17763
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name SYDNEY-PC
System Manufacturer OriginPC
System Model CHRONOS
System Type x64-based PC
System SKU To Be Filled By O.E.M.
Processor Intel(R) Core(TM) i5-9600K CPU @ 3.70GHz, 3701 Mhz, 6 Core(s), 6 Logical Processor(s)
BIOS Version/Date American Megatrends Inc. P1.50, 12/28/2018
SMBIOS Version 3.1
Embedded Controller Version 255.255
BIOS Mode UEFI
BaseBoard Manufacturer ASRock
BaseBoard Product Z390 Phantom Gaming-ITX/ac
BaseBoard Version Platform Role Desktop
Secure Boot State On
PCR7 Configuration Binding Not Possible
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume4
Locale United States
Hardware Abstraction Layer Version = "10.0.17763.831"
User Name SYDNEY-PC\Sydney
Time Zone Eastern Standard Time
Installed Physical Memory (RAM) 32.0 GB
Total Physical Memory 31.9 GB
Available Physical Memory 22.4 GB
Total Virtual Memory 36.6 GB
Available Virtual Memory 24.8 GB
Page File Space 4.75 GB
Page File C:\pagefile.sys
Kernel DMA Protection Off
Virtualization-based security Not enabled

Hyper-V - VM Monitor Mode Extensions Yes
Hyper-V - Second Level Address Translation Extensions Yes
Hyper-V - Virtualization Enabled in Firmware Yes
Hyper-V - Data Execution Protection Yes

The spec I was most interested in would be your graphics card, bug as you have cropped it out of the video, I had to ask. As far as I see, that info is not included in the specs you posted above either.

1.15 changed the way how chunks render. Previously, the game would just stop rendering more chunks if it meant you could get a higher framerate. This is no longer happening, it will render all chunks it should render as long as you can still get more than 30 fps.

Thus, framerate drops are to be expected with such a high render distance if you aren't using really high-end hardware (i.e. graphics card). Hence I wanted to know what yours is.

Seems like we already got a ticket for this though, see MC-164123. But consider lowering your render distance if you want to get a better framerate.

Ah my bad, and apologies for the lack of showing graphics card, the one I'm using is Nvidia GeForce RTX 2060.
https://gyazo.com/a85d45f0b33963a6fa5028cb7aea7379 Hopefully this screenshot can answer a few questions.

Ok, thanks! It seems like hardware-wise, you're good.

The reason you were getting that high FPS in 1.14 was probably because you had the FPS limit set to maximum, which meant that the game would skip rendering chunks. Now in 1.15 it will render more chunks. This was an intended change. A consequence of that change is that lowering your render distance will now actually cause your game to run with higher FPS, previously the higher your FPS target was, the fewer chunks would get rendered.

For an in-depth explanation about this by a dev you can read this: https://www.reddit.com/user/sliced_lime/comments/e00ohm/a_word_or_two_about_performance_in_minecraft/

I understand much better now, thank you very much for the explanation!

this may be causes in part by your distance setting, basing how game now prioritize settings and 2 more kinda major bug fixes. Few hours ago I'd say that this is completly caused by this, but I found that Mojang comfirmed "performence drop" from 1.14.4 to 1.15