Yes, 1.13 added in Phantoms. When they start spawning you will have 1 spawn first and than if you continue to stay awake for days and days more will spawn in the end killing you in a few seconds.
Minecraft uses your CPU more than your graphics so if you do not have a good CPU your FPS is gonna be horrible. The fact that you also are using shaders means not only is the CPU being worked MORE, you didn't even try to allocate more of that 32 gig ram. as for the Vsync option, yes... do that it works wonders.
Thank you, I attempted the double plant mechanic and the sand decided to fall when I took away the plants. I will attempt it again because I think I did block update.
As for the fire trap it's basically using the fire starters that you craft using the nether materials. The poison repeater I was thinking of using the repeating gate with 4 repeaters and a quick place and break of a redstone torch but I wanted it to work as a switch, if a player triggers the redstone it does like a FAL burst or something of the sorts and stops.
From my research, Minecraft focuses mainly on CPU usage. Your Intel® Core™ i5 processor might not be able to run 1.13 due to the large amount of animation the sea brings to Minecraft. It really depends on how new your PC/laptop/Tablet is and how your CPU is running. I would go into your Task Manager<Performance to see how it's running while Minecraft.exe is open.
If it is your CPU I'd say invest in a new CPU or computer/laptop/tablet. My brother's PC is brand new and has literally the top specs a gaming PC has atm and without optifine the ocean murdered the FPS with 9 view distance. The game has a horrible rep at bringing these machines to their knees so don't be upset about it too much.