rollover into new employer plan so all my money is compounding
This is not an issue. Your money will compound the same whether it's in one account or two.
Suppose you have $100 in two accounts, each of which earns 10% for two years. In one year you'd have $110 after the first year and $121 after the second year in each account for a total of $242. If instead you put it all into one account that earned 10% for two years, you'd have $220 after the first year and $242 after the second year. So having multiple accounts has no effect on compounding.
The main benefit or rolling a 401(k) into a new employer's plan is that all of your money is in one place. This is not a financial benefit but an administrative one. You don't need to track it in multiple accounts, you can easily rebalance your entire portfolio, etc.
Another option is to roll it into an individual IRA. The main benefit here is diversity of investments. While your old 401(k) may only have 5 to 20 investments depending on the provider, rolling into an IRA will open up a whole world of investment opportunities. Now, this is sort of like going from a vending machine to a candy store, where the number of options alone can be overwhelming, so that may not be of great benefit to you.
Another benefit is that you might save some money in administrative fees, but that shouldn't be a huge burden.
I would also take a more critical look at age-directed investments. Yes they rebalance for you, but often have higher fees and may not have returns that are better than just investing in a few index funds and rebalancing yourself every year, reducing your risk as you get closer to retirement. Most providers even have advisors that will help you do this periodically, especially once you've saved enough to be a "valued customer".
All that to say that if you like your old 401(k)'s performance after comparing it to some index funds, you don't have any significant administrative hassles, then there's no compelling reason to move it. You're not "losing" anything financially just by having it split into two accounts.