A better system would have been to pair "Minimum Level" and "XP Penalty" values for each race. So, for example, you might say "Minimum Level 2" for the Drow, and assess a 20% XP penalty; thus, a Drow would not be playable in a game of lower than second level, and the Drow would suffer a penalty of 20% on all XP (including the starting amount). So, if you start a gamewith, say, 1,500XP and 1,250GP (a bit of the way to level 3), a Drow would have 1,200XP and 1,250GP ... still second level, but a bit behind the other players, and under a penalty to earned XP. Thus, the Drow will level slower than the other characters ... probably hitting 4th level about when the rest of the party hits 5th. Eventually, their lower individual ECL will garner them higher XP awards, to the point of roughly balancing out ... so once they fall a level or two behind, they would probably not lose any further ground in relation to the rest of the party.
OTOH, a Mind Flayer might be "minimum level 10, XP penalty 30%" ... as a sort of pick numbers out of thin air sort of example.
Some races might have a high minimum level, and little or NO XP penalty.
A few (like the poor, best-upon Kobold) might have an XP bonus ... say, 10% (which, again, would eventually level out, once the kobold got a certain number of levels - probably one, maybe two - ahead of the party).
Unfortunately, I for one am not up for crafting a system like that, which can be quantifiably applied to the races and monsters already presented within the panoply of WOTC rules (let alone those from Third-Party products)..