Although there is no any new released updates from Quicksilver development teams to solve its slowness while launching, I still stick to it until now.
The main reason is that I have used Quicksilver all the time and found it boosted my productivity. One example is when uploading photos to Flickr.
We all know that Flickr has released its Flickr Uploadr for you to easily upload your photos separately from your web browser. It's such a good application but the only minus point is the upload window can't be closed. It can only be quitted.
So everytime you want to upload new batch of photos, you need to launch Flickr Uploadr first, before starting to drag and drop your photo files.