Recent versions of Windows have provided indexing of file contents that allows for fast searches over the entire contents of your hard disk.  This includes pdf files, but the default filter file only works with 32 bit Windows.  It is  simple process to fix this problem by downloading an updated filter file.  for full details see:

Indexing pdf content

The indexing process takes time, but once completed it is updated in the background with no noticeable effect on performance.

Once indexing is complete, the Windows File Explorer provides very fast searches of all indexed folders, and fast preview of selected files: