Neither. You can speed up the game by simplifying the check conditions for events. This can be done by using more country flags for complex events rather than doing a full even every time an event triggers. For example, a hundred events all checking for consciousness above 2 or something can be simplified by having a country flag be triggered with it over two. Less calculations take place this way. Additionally, many of the flavor or historical events that don't actually do anything can be set to ai=no as the ai buff/debug makes them very ineffective. Also, national focuses slow the game quite a bit and do not actually work very well for the ai as they only work on accepted pops and the ai doesn't take this into account. This can be fixed with a line like if ai =yes then only allow if any prov in state is core this and or borders core or borders a province with majority accepted culture or has majority accepted culture. For this go to paradox forums and the divide by zero thread and search badkarma12, I already made a file that does this. As for the tags, the don't actually slow down the game at all, only when they actually exist in the game. Theoretically they could slow down the game by adding another rebel faction but this is negligible at best. The thing that slows down. The game the most is the economy, the more types of goods the worse it gets, and the inclusion of more reforms (through pop wants and more conditions). Everything else is negligible, unless an even or decision is broken and constantly firing. Oh yea, you can also include the large address awareness patcher to the mod download, as that speeds the game slightly and fixes a crash once in a blue moon. Oh yea, and the game could also be sped up significantly late game by the merging of telegraph lines and railroads as just industry. Also, more pop attrition would help, like instead if every casualty being .2 make it higher. 1 pop is 5 people, but considering the period ir actually is accurate to kill all 5, what do you think happened to the families when the provider died? Also, you could remove some typed of rebels, this will happen a lot. For example, just combine the reactionaries with the carlists, and add an event for if Spain is a monarchy or something and is occupied by reactionaries, the carlists come to power. At the very least, the red shirts could be removed and just replaced with more pan-nationalists. Also armies, if they hit 0 or too low a pop you can just destroy them instead of having them reinforce and take up a ton of memory resources, especially late game. Also some province manipulation might be in order to remove the ability to build naval bases in part of Ob in northern russia, as right now it is totally possible to have ships trapped in a lake.
Edit: oh yea ,for all the peasant rebels, like the reactionaries, liberals whatever (or just all rebels) remove the ability to use generals. That might help too. And turn on unit merging for all rebels, this helps a lot, especially in China or late game. 100 small brigades takes up a lot more memory than 1 giant one.
Edit 2: back to the event thing, you can disable all of the 2nd are response events for the ai for wars and such. Just change the initial even to declare war right away and the second event to just be text for the player only, (if an ai declare war on player). The ai doesn't need to see the text.
https://www.reddit.com/r/Vic2Mod/comments/341m59/what_will_speed_up_the_mod_more_removal_of_tags/