According to reports I've read on line (I've never had the SX40), the lag time is greatly reduced in the SX50. Do a Google search for "lag time" and SX40 SX50.
Nice explanation about lag time over at Steves-digi.
Another occasional problem I found with the SX40 is ‘focus hunting’ sometimes on subjects and scenes I would least expect. I find the SX50 has much improved in that regard.
Quote hhgttg: Life is wasted on the living.
filibuster (Bromsgrove, Worcestershire, UK)
does this camera have lag like my sx40???
As Monica mentioned, lag time on the SX50 is very reasonable, and as filibuster mentioned, much improved over the SX40. If you are interested in further differences between the two cameras, you'll find a lot of information on the SX50 with comparisons to the SX40 in my review posted here. I hope you find it helpful.