How can I make kint() load faster when debugging twig templates?
There are two other ways other users have mentioned for setting the max output levels in addition to the settings.php method mentioned in the question, plus a couple other ideas below:


Create a /modules/contrib/devel/kint/kint/config.php file and add / modify the line $_kintSettings['maxLevels'] = 3; (by @mdrummond on Slack)
In a preprocess function, add the following: (by @thpoul on Slack)

kint_require();
Kint::$maxLevels = 3;

Be sure to never click the + sign, that shows the entire tree. Click the block instead. You can click the right arrow to open the output in a new window for easier viewing (like when the output is in a block). (by @cwightrun on Slack)
Instead of using kint(), create a preprocess function and use a debugger to explore the variables. (by @danny_englander on Slack)
Pass kint() a specific variable instead of making it roll through the whole tree (by @No Sssweat below).
If you just need to know what variables exist, you can just view the keys by doing a {% for key, value in _context  %} loop (by @mortendk below)