Problem - Cannot obtain full bandwidth of 30 Megabits thru router

Preliminary info
Network at Home
Long Island - NY based
Cable Company - Optimum Online
Cable Modem certified to 30 Megbits

1] BEFORE UPGRADING BANDWITDH
Original Config
Cable modem as stated above
Linksys BEFSR41 router
SMC EZ Switch 10/100 16 ports
6 computers all running XP Pro with Gigabit NICs
Bandwidth/speed tests 5 Megabits Download / 2 Megabits Upload typical

2] AFTER UPGRADING BANDWIDTH TO 30 Megabits
Same exact configuration
Bandwidth/speed tests 6 Megabits Download / 2.5 Megabits Upload
typical

3] ROUTER BYPASSED
Removed router and switch from system
Connected 1 PC direct to cable modem
Bandwidth/speed tests 27 Megabits Download / 5 Megabits Upload typical

4] NEW CONFIGURATION
Same cable modem
Upgraded router and switch
Linksys RVS4000 Gigabit Security Router
SMC EZ Switch 10/100/1000 24 ports
6 computers all running XP Pro with Gigabit NICs
Bandwidth/speed tests 12.5 Megabits Download / 3 Megabits Upload
typical

5] Performed Switch Bypass test
Connected 1 PC direct to router gigabit port
Router remained in system connected to cable modem
Bandwidth/speed tests 12.5 Megabits Download / 3 Megabits Upload
typical

6] Repeated router bypass test
Removed router and switch from system
Connected 1 PC direct to cable modem
Bandwidth/speed tests 27 Megabits Download / 5 Megabits Upload typical

7] Notes
Router is obvious bottle neck / limiting factor of bandwidth transfer
to computers on LAN
Multiple calls to Linksys - Always get transferred to India for help.
All answers from India - NO HELP
NO response from linksys direct in CA - All calls go un-answered.
Linksys web site - NO help
Searching internet is NOT giving me the answers I need

8] I need help !!
Any info on bandwidth/speed vs 10/100/1000 LAN?
Any web site(s) that answer these questions would be appreciated.
All info will be presummed as 1 computer connected to LAN for specs
What is Burst max bandwidth/speed for each LAN 10 - 100 - 1000?
What is the Sustained bandwidth/speed for each LAN 10 - 100 - 1000?
What WAN spec is needed to sustain 30 Megabits from router to cable
modem?
Have played with all settings in router - No change in performance.
Any recommendations for a router to eliminate bottleneck?
TIA