From Gnash Project Wiki

Limits

Known limits are:

• ScriptTimeoutSeconds - responsible for that dialogue that pops up after 15 seconds.
• MaxCallStackDepth - default to 256, max depth for function call stack
• MaxInheritanceCrawlingDepth - the number of parents crawled when looking for getter-setters. 255 by default (253 for SWF5-?)

Gnash

Gnash implements ScriptTimeout in term of number of back-branches. Everytime the program counter is decremented (due to a Branch back), a counter is incremented. When the counter exceeds 65535 the script is aborted.

For MaxCallStackDepth Gnash uses a limit on function call stack.

References

• http://flasm.sourceforge.net/#scriptlimits
• http://rewindlife.com/2003/12/09/undocumented-flash-player-7-features-recursion-limit-and-script-timeout/