Bear in mind this is NOT 2G, it's still 3G/3G-HSPA (quasi-4G) but it's throttled to 128Kb. Difference?

EDGE: latency pings: 700-1000ms
HSPA: latency pings: 80-400ms

[NOTE above ping times should be to servers in the US as when you roam you are essentially tunneling data from carrier you are roaming on back to T-Mobile. You are NOT getting an internet connection in the country you are roaming in but a tunneled connect to the internet via T-Mobile in the US. All data roaming works this way regardless of carrier - ping times are higher when roaming as all data has to roundtrip travel across longer latent links - when doing speedtest also if you can turn off gps/location then it will do IP location which will be in the US and allow a US server to be picked closest to T-Mobile's data exchange point to Internet]

Hint: If you see multiple carriers you can roam onto ; try another one. First reason; you may be seeing a carrier with a locally saturated network ; second reason; the backhaul that carrier has to roaming partner may be saturated.