I shoot RAW, but would prefer to have computer files in TIFF. For me, TIFF opens much faster and I can use external programs (some of which I've written). The sacrifice in disk space is worth it. Is there an easy way to do all this conversion up front in Lightroom? Or do I have to export things and synchronize the directory?
Export to TIFF, but don't delete the RAW until you need more space, and then purge the oldest.
I'm not aware of any direct way as Lightroom is designed to be non-destructive.
Do an export to TIFF with the option to import to catalog after export. Then delete the RAW files and remove all the missing files from your catalog.
I would like to suggest that you give editing in raw another chance and at least don't dispose of the originals.
Lightroom tools may not provide as much control over the contents of an image as other tools like Photoshop, but they are based on best practices. One can read 335 pages of Image Sharpening and painfully apply the knowledge via luminosity layers, masks and other tools in Photoshop on each image individually, or move a slider in LR for pretty much the same effect.
Lightroom editing is non-destructive and reversible. Photographer may take his/her decade old image and reprocess it today, applying better demosaicing, better highlight recovery and with ten more years of working experience with digital data for a better result. That's not possible with already converted TIFF.
My personal favorite feature is the ability to generate multiple outputs from a single edited source. I no longer need to have a separate copy optimized for a pro lab, another for my 17" printer and another optimized for web.
LR can generate the TIFF at any time in a second. So if editing in a specialized editor is necessary (conversion to B&W, LAB editing, image analysis etc.) it can be always done.
If disk space is not a problem then is there a reason why you can't keep both RAW and TIFF versions of your images?
I shoot in RAW, then use my SLR's bundled software to preview all of the images, deleting any which are hopelessly composed, out of focus, blurred, or otherwise worthless. Then I use the software to squeeze everything I can out of the RAW image, making adjustments for lens distortion, chromatic abberation, cropping, exposure, white balance, contrast and sharpness.
Only once I'm happy with the processed images do I batch process the RAW files to 8-bit EXIF TIFF images. Bizarrely TIFF images are larger despite containing less information, so I have no desire to delete the RAW files. You have much more latitude for reprocessing images if you keep the RAW file.
After the batch process is finished I have a folder called, for example
/2015/2015_01_02 which contains the RAW files, and then a subfolder called
/2015/2015_01_02/TIFF which holds the TIFF files produced by the batch process. I keep all of these, even though one shooting session can easily add 10GiB of files to my hard drive.
If you are intent on deleting your RAW files, then at least remember to export your processed images to 16-bit TIFF. That will give you more leeway for any future editing. The 8-bit TIFF files quickly lose subtletly if you try to adjust curves/levels or colour balance.