Before reading the rest of my post, you should know that the title of this thread is very misleading. As I hope you'll understand from my post, there is no question about this issue at all, there shouldn't be any questionmark. It's also not just restricted to builders. Explained below is a massive "bug" that affects every person playing this game, including you.
This thread is about a "bug" in the game which causes the time to be inflated (details below). The "bug" affects everyone playing this game, and is easily tested and proven. Sadly many people don't realize it until they're made aware and don't realize that they're being duped. If you, while reading this, are in that group... well, keep on reading
This "bug" has been documented since at least November 2012, and has most likely been around since the beginning of CoC. See the bottom of this post for links to earlier threads.
The concepts affected by this time inflation are:
- Builders constructing or improving a building
- Laboratory upgrades
- Resources being generated (mines, pumps, drills)
- Troops and spells being created
- Clan castle request timer
- Hero sleep timer
Not affected:
- Shield time
- Push notifications
The time added (or 'lag' from now on) isn't smoothly spread over the duration of the upgrade; rather it's added in increments of a few seconds upon performing certain actions. Testing used to point to between 5 and 5 1/2 seconds added per increment, although it has recently increased with all reports averaging 10 seconds and peaks of 15 seconds added per increment.
The known causes all converge to the loading of one's village:
- Opening up and reloading the game (includes after "Are you there?" message)
- Viewing replays
- Returning from any visited village, which includes:
--- Playing or just viewing a single player mission
--- Attacking or just viewing through revenge
--- Attacking or just viewing through matchmaking (note: you only return to your own village once regardless of how many bases you view at a time in matchmaking. You don't get multi-penalized as far as I know)
--- Viewing other players' bases (top players, clanmates, people in general, revenge preparation, etc, etc)
- Finally, according to Supercell's own support team, your base is also affected when it is loaded (for attack or viewing) by other people than yourself. This means that your times will also get inflated, even when you don't even spend a second online yourself. Every time a player gets the option to attack you (whether they take it or not) and every time someone decides to (for whatever reason) just check out your awesome base, time gets added to all the things affected.
It is very easy to test the problem and see it with your own eyes. A demonstration of how to do so is given in this video:
*video link*
Oh, and you thought the scam couldn't get worse than this? Well, it sure can. If you spend gems on boosting your barracks, spell factory, or mines/pumps/drills, the lag gets 'boosted' as a side-effect too. So you're just imposing a bigger lag on yourself. Thanks Supercell, just what we were looking for, paying for more lag! Lol...
So now you are probably thinking something along the lines of "well, if this has been known for over a year, why is it still here?"
There have been various people in this community who noticed it early on, and have worked hard to raise awareness and offer solutions. Throughout the threads, many solutions have been offered. Just a few examples include:
- Fixing the bug outright (obviously preferred and required)
- Effective compensation by subtracting 5 seconds for all affected issues per village load
- Compensation in the form of reduced base building times (e.g. 4d 22h instead of the listed 5d, so that with the lag accounted for it is roughly the 5d that is to be expected)
- Other forms of compensation, such as an increase in gems, so that those can be spent on instant-finishing the lagged portion of things.
- And even more... these were just off the top of my head
So, with all this knowledge and wealth of ideas and solutions, what does Supercell do?
Steve (Supercell) has stated repeatedly that there are no plans to fix this bug.
tl;dr

The more you know....I tested this out and its actually true. To test it out, you need
1. A second device or a timer on your computer
2. Clash of Clans open
How to test it out:
1. Go to your barracks and train 10 barbarians.
2. Start the timer as soon as it hits 3 minutes sharp.
3. Close Clash of Clans and remove it from open tabs
4. Re-open Clash of Clans
5. Go back to the barracks
6. Compare new training time to the original time.
Anywho, I need like ~15 more wall pieces to be upgraded then my walls will be set. Luckily this 1 gem boost is helping me.