The latest kernel is able to index about 500 HTML documents per second on 2GHz PC. Searching is not limited by the document collection size, rather by the hit list size. If documents are ordered by some factor (i.e. PageRank), then the querying is realized in a (rather) constant time. If not, then you can consider query time related to reading 6 bytes per every hit of a hit list.
Indexing performance is smaller than the performance of egothor 2.x. However, the kernel is still able to index several hundred documents per second.