I am using your tier 4 furnace, which should give 116 copper plates per second, but I am unable to get it running faster than cca 60 pieces per second ( it is using only half of Transport belt pro 3) as you can see here:
https://imgur.com/xDhdNbm

Adding speed modules did not change anything except power consumption.

EDIT:
Tested again in sandbox mode with no aditional mods but with the same result.
https://imgur.com/jBEaxaD

Version of game 0.17.34

Yes, I also see this error, the counting formula is actually a simple speed of one electric furnace = 2 units. We multiply 2 * 48 (the number of ovens included in the recipe) But at what point did I have time to break it?)) Now I will correct this error. I will solve the problem with speed modules later as soon as I have time. Thanks for finding the error.

I don’t have time right now, as soon as I’m free, I’ll try to solve the problem.

How fast this crafting machine can craft depends on the speed of crafting. 1 second long recipe take 1 second to craft. 0.5 means it takes 2 seconds, and 2 means it takes 0.5 seconds. And that means the description was not true to the furnaces, because of a misunderstanding of the formula. I spotted it on the stopwatch in about 60 seconds. The 5ur furnace melts 3,500 copper plates, the melting time of which is 3.2 seconds. And oven 1ur 890 plates. It is fair to reduce the cost of the recipe in two. Speed modules work, it was tested using production counters.

I'm still having production speed issue with furnace 4 and 5. It's not producing as fast as it should be. 4 is barely faster than 3 and it should be twice as fast. 5 is as fast as 4 and should be twice as fast.

Version: 0.3.5
Date: 28. 06. 2019.

The formula crafting_speed is changed to an integer.
Furnaces level 1 has a crafting speed of 50
2 levels 100
3 levels 200
4 levels 400
5 Level 800
As you can see, the speed of the next furnace is 2 times the previous one.
You can find all these values in the furnaces folder at the end of the furnaces.lua file and experiment with them. crafting_speed =

I understand the mathematics behind the crafting speed, but there is some kind of bottleneck. Other mods have had to create their own recipes in order to bypass this limit. A single recipe can only be crafted once every game tick, so once you hit the 60 recipes per second, it simply can't go any faster, no matter what the crafting speed says.
The other mods simply create recipes that produce more of the target resource for a single recipe, so instead of 1 iron ore = 1 iron plate every 0.5 seconds, they do 10 iron ore = 10 iron plate every 0.5 seconds. The new recipe is 10 times more effective than the original, while still executing the same amount of times, therefor not being affected by the '1 recipe per game tick' limit.

You can think of a function that will add new recipes in the game for 10 pcs. etc. but is it worth it? Honestly, I don't want to. At the moment I left the factorio and do not devote so much time to either the game or the mods. Initially, the furnace was made for myself to save space, then I began to look differently, in front of the player a whole planet). Solving your logistic tasks by building compact factories is wonderful.
The forum has mods that multiply the production of crafting.

Hello, I'm having the issue as well, maximum of 60 plates per second.
.

del

Version: 0.3.6
Date: 09. 07. 2019.
In the settings, the ability to turn on the furnace recipe change has been added, this will lead to an increase in production by two times, as well as the time and resource costs will increase by two, which will allow smelting more products in the furnaces. Default off

It is recommended to include at later stages of the game when you have investigated the technology of the furnaces.

It does not work with chemical furnace recipes, and the bean already has a high time cost in these recipes and the production of 5 or more pieces

There was no full test, because I am not at all in the game, and there are other things to do, but I will drop in from time to time

Added new oven recipes, now time, ingredients and result multiplied by 10. This should solve the problem of crafting speed limits. Previous bugs fixed.

I think now this question can be closed).