Neat. My rough understanding is that carriers here route traffic through SEACOM, EASSy (and likely others) to minimize cost and traffic. I don't think I can choose SEACOM specifically -- but I'm always up to test Cunningham's Law.
Your traffic traversed through SMILE>Zantel>Tata .. You may not be able to influence the best path to reach Google through Smile even though Zantel might be multihomed (unless the best path changes). I'd recommend testing from other providers such as SPICE-NET-TZ, TZ or simbanet-tz,TZ etc. [ Look above at the Seacom's downstream adjacent AS link I provided to find if you can use any of those carrier instead ]
# whois -h whois.cymru.com 41.138.222.196
AS | IP | AS Name
327692 | 41.138.222.196 | SMILECOMMS,UG
# whois -h whois.cymru.com 41.73.194.97
AS | IP | AS Name
36930 | 41.73.194.97 | Zantel-AS,TZ
Wonder what your latency would be with a SEACOM(AS37100) traversal, http://en.wikipedia.org/wiki/Telecommunications_in_Tanzania
Here are your downstream carrier options : http://www.cidr-report.org/cgi-bin/as-report?as=AS37100&v=4&...