No — rasterizing PDF to TIFF turns text into pixels. If you need searchable output, keep the PDF as a PDF and use a text-extraction tool instead. Image output (TIFF) is for visual display or further image processing.
About 30-90 seconds for a 100-page PDF -> TIFF at 150 DPI. Higher DPI doubles or triples the time. Pro users get more parallel workers — 100 pages typically renders in under 30 seconds for them.