They say in racing you can divide gaining time into three sections: the line; corner exit and "braking and entering".
Time gained from mastering each part, for each corner, is measured in that order. Seconds for the line and corner exit, and tenths for the braking phase and entering the corner.
The last part, even though the time gains are relatively small, are where the hardest improvements come from.
That's why the brake pedal becomes the most important of all three, though that importance with regard to lap times is often either underestimated or overlooked altogether.
What does that mean for a sim racer? It's quite common for drivers to upgrade their pedals. The Fanatec range with load cells are popular. But those are quite expensive.
An alternative is to mod the pedals that you already have. The Logitech G25/27 is a very popular wheel, shifter and pedal set. The problem with the brake pedal is that it's not progressive. The same amount of pressure is required all the way through its travel. But even with a potentiometer inside rather than a load cell it can be improved significantly.
The first upgrade for the pedals is a Bodnar cable. You can learn more about it and purchase one here. With this cable you connect the pedals directly to your computer through USB, no power required even from the USB port, and the pedals resolution increases from 256 to 1024. That's quite an improvement in resolution.
The second upgrade is to the aforemention brake pedal. This upgrade is a little more invasive and requires opening the pedals casing, which, therefore, may mean voiding the warranty. It's a simple procedure, though you should allow an hour to complete it.
There are many pedal upgrades available for the G25/27 pedals. The GTEye modification replaces the smple factory spring with a progressive spring. With that improvement it becomes easier to find the threshold braking point, making braking more consistent and efficient. You can learn more about the GTEye modification here. The benefit of using this brake pedal modification is that while pressure differs as brake pedal travel increases, the pedals don't have to be hard mounted. It's probably the most gentle of its type in that regard.
With that installed it's useful to "short calibrate" the brake pedal so that the threshold braking point is in a part of the brake travel range that feels good, and is therefore easier to replicate.
These simple and relatively inexpensive upgrades will not only improve your lap times, but they will also at least extend the usefulness of the pedals, and quite possibly satisfy your need for better pedals completely.