Is there some way to load thumbnails for a selection of photos, other than scrolling through them page by page, waiting for them to render? I'm aware that I can build previews of varying quality, but this takes forever, and thumbnails are all I need to view for this particular task. Does Lightroom have a thumbnails-only build function?
Adding a bit of clarification to the Question above: your comment in another answer included this:
How can I create a set of thumbnails for a given folder, without having to to build a full preview, and without having to tediously scroll though the folder, waiting for each page to load? Does such a function exist in Lightroom?
Lightroom does not need the previews, they are provided for you. If building the previews are taking a long time, you might simply need to adjust what previews Lightroom builds, and when.
The key is setting this via the Import dialog. It looks like this, and pops up when you do an import of photos:
It is important to remember that the Import dialog simply repeats what you did last time, so be sure to change this here, and it will repeat this choice in future imports.
When importing the image, be sure to select 'Minimal' under "Build Previews". This will basically grab the JPEG image embedded, or create a very small preview image. You can then sort thru the images with the Library module.
Later you can ask Lightroom to build Previews. To do this, simply go to the menu and select Library>Previews>Build... and choose the previews you wish Lightroom to build for you.
I can build previews of varying quality, but this takes forever
That's because it's a bit of computational effort to build those previews and there's no way around this.
that preloads a selection of thumbnails?
There's no such thing as "preloading" them, because they have to be calculated nonetheless. If you choose a lower quality it should be faster, but it still has to happen, because you are asking for LR's interpretation of the data and there is no interpretation without the actual interpretation.
What you can do of course is to only import the selection of images that you are interested in.
An option is to do something else in the meantime: backing up the files, cleaning the gear, sleep, etc. Sitting in front of a batch process and waiting for it to finish is never a good idea because no matter what you do, it will never be fast enough.
I'm going to guess you want the previews up to cull or select on a time deadline? (Some more info on use case may help people answer). I love Lightroom, but it just is not the right tool for fast processing of new shots. Most raw files include a preview already rendered, but Lightroom ignores (mostly) and builds its own to accommodate presets, etc. That's good mostly, but bad if you are in a hurry and want to cull.
I shoot sports, and I want to sort through my shots and choose maybe 10% to process. It takes forever if I import to Lightroom first. Instead, I use a separate tool to cull (and sometimes rate as urgent vs soon), then import that far smaller number into Lightroom to process. I use Nikon ViewNX2 which is free, but the premier tool for this kind of thing is PhotoMechanic. Both will let you drag and drop the selected images into the import of Lightroom.
Beyond that in Lightroom, using the build option to build the size you want up front is the closest you can come to controlling that speed (well, or buy faster hardware, which always helps in photo processing but is not a pleasant solution).