The 25p map is a "historic" map, which means that balancing is really not taken into account. It's normal for one country to be far ahead of another on such maps. I don't know what France and Romania's starting situation is.
Even on balanced maps, Yugoslavia is often significantly ahead of other countries in terms of tonnes of resources produced on day 1. The reason is double resource provinces. A double-oil province produces about half as much as a double-iron province. Double rare materials provinces produce even less. So a country like Finland (?) that has a double rare and a double iron will produce far less tonnes of resources than Romania with their double iron and double goods. Same goes for the single-resource province count. In my most recent game I'm playing S.US with three rare materials provinces and a double oil. That's far less resource tonnage than Algeria who only has one rare material province and has two high-producing doubles.
The double-resource situation can be further aggravated if one or both of a country's doubles are on water, where they can increase the production gap further with harbours.
If after 10 days you have lost ground on the production rate of the AIs (regardless of any "historical" starting imbalance), reconsider your build strategy. Have you built infrastructure L1 or L2 on all of your core resource provinces? Have you upgraded all your ICs? Have you built a new IC on the double-resource province that started without one?
