It depends on the Slingbox (server) and Slingplayer (client). If you're using Slingplayer Mobile then yes, that's high performance. If you're using Slingplayer Desktop or Web Slingplayer then it is marginally above minimum requirements for SD streaming. If you're using the Slingbox Pro-HD, you wouldn't be able to take advantage of its HD streaming capabilities.
Here are the specifications.
- HD Streaming: 3 Mbps or higher
- SD Streaming: 600 Kbps or higher
- Mobile Streaming: 150 Kbps or higher