ProgressSetupDialog is shown by enablesetupdlg action in msi InstallUIsequence but first encrease of the progress bar happens at MSIInstallJRE (installer.dll).
There are many msi actions happens after ProgressSetupDialog is shown and it takes about 10sec on my machine. All that time progress bar doesn't move and it looks like installer is frozen.

For the offline installer the situation is worse since first encrease of the progress bar happens after core.zip is unzipped (so in about 22 sec after ProgressSetupDialog is shown on my machine).
After that progress bar increases very fast but usually it doesn't reach the end of the bar before window is closed.

Progress bar should better reflect installation process to avoid user's confusion.

My machine sysinfo:
OS Name: Microsoft Windows XP Professional
OS Version: 5.1.2600 Service Pack 3 Build 2600
Processor(s): 1 Processor(s) Installed.
                           [01]: x86 Family 6 Model 15 Stepping 13 GenuineIntel ~1995Mhz
Total Physical Memory: 2 038 MB
Available Physical Memory: 736 MB
Virtual Memory: Max Size: 2 048 MB
Virtual Memory: Available: 2 008 MB
Virtual Memory: In Use: 40 MB