I made a slime farm in a survival world, i have check every information about spawn and everything i get on google, the slime farm works, but too slow, take several minutes to spawn a slime, anyone please could help me?
did you light up all the caves and dark spots within 128 blocks (in each direction) of your slimer? Having dark spots (including on the surface) in this zone will mean less slimes will spawn because the slimes share spawn space with creepers, zombies, skeletons, and witches. Basically, if you're not in a swamp and hunting slimes on the surface then only 10% of the spawns will be slimes. What's more salient, though, is if non-slimes are spawning and you're not killing them off that reduces slime spawns even further because of mob caps.
In your own screen shot your debug screen is showing 92 entities loaded. That looks suspiciously like 70~ mobs plus a few passive entities or items laying around. Also just in your screen shot I can visibly see tons of lips and little areas that almost surely are not actually lit up to 8. Each of those little spots has a much higher chance of whole a list of mobs spawning there compared to 1 specific rare mob type (a slime) spawning on the bigger platform.
The problem almost without question is because there are 70 other mobs hiding in all the spots you missed within 128m of where you are standing. It is really difficult and time-consuming to actually light everything up properly in a 256m cube... Look at your F3 light meter for 8+ as you go and good luck..
Slimefarms aren't what they used to be. Even in perfect conditions, it seems that slime spawning has gone down a lot, and in addition, they now despawn as well, like other mobs. I build a slimefarm pre-1.8 and had so many slimeballs that i didn't know what to do with them. After i updated to 1.8 it suddenly almost stopped working without changing anything to the design.
You don't need a quad slime farm for good rates, trust me. I have a single chunk farm in 1.8 and gets way more slime balls than I could ever use. It does look like you're standing too close to the farm for it to work. Back up a bit and see if that helps.
Besides that the only thing I can think is that you missed some caves. If you don't mind being a little cheatly, you can open your world to LAN with cheats enabled, type /gamemode 3, and be able to fly around through solid blocks and if you fly underground inside of the stone and other solid blocks, it will act as an x-ray and you can see all the caves nearby. You'd be surprised on how much you can miss, there is ton's of caves that aren't connected to anything. Other slime chunks in the area could also be taking away from spawns as well, since they ignore light levels in slime chunks. You'll need to slab up or flood caves in other slime chunks.
Thanks for everyone who help me so far, well in order to leave no doubt i have used cheats to clear all the space 140m away in every direction and fill the flow with glowstone. this picture are in peacefuly difficulty so the number of entities are passive mobs.
I still have the spawn rate issue, above the structure are solid, have no caves......