When we run through the whole (major) upgrade path(from 2.5 to 3.0, from 3.0 to 3.5 and from 3.5 to 4.0) we notice that the latest upgrades become very very slow(eg. from 3.5 to 4.0).
If we install 3.5 clean and upgrade to 4.0, this upgrade will work much much quicker.
It seems that no one has an answer for this problem.
Maybe can anyone help me in telling how I need to investigate this problem? Are there some indicators in the logfile why(are on which action) the upgrade takes that long?
The most effective method for isolating this behavior would be to create a verbose log of the installation that takes the longest amount of time to complete, and then look through the log to see where the biggest jumps in timestamp values occur (MSI includes a timestamp on every line it writes to the log). Then, once that range has been found, look up in the log from that point to see what the action name is that is currently running.
