Interesting, Maksimus.

One thing against increasing the build time of palace buildings, though. The AI will quickly build the palace as soon as the city can be upgraded, they are hardcoded to do so. If you set the build time at a huge amount, the AI will just sit their building palaces for years. They won't be building infrastructure or MICs and will have a poorly developed town with little recruitment options as they spend those years upgrading. (Just to be sure, no offense to you intended by this post.)