[EdgeRouter Lite 1.9] Slow speeds after a few days of uptime

This has been going on for quite some time now. I will notice that speeds start out at 250Mbps when the router is freshly booted but after a few hours or days of usage the speed comes to a crawl to about 20-30 Mbps. I

• Directly connecting my PC to the modem resolves the slugishness
• I noticed this issue on version 1.8 as well. I was hoping an update to 1.9 would resolve, but as you can see, it has not.
• I've verified my switch is working, along with the PC being used to test this ( speed tested between two computers in the same network)
• I've tried directly connecting my PC to an unused ERL port (eth2, contains no vlan/virtual interfaces) and it still is giving me the slow speeds
• I've verified ipv4 forwarding and vlan offloading is enabled
• I've tried temporarily disabling all of the firewalls rules but it doesn't help
• Rebooting the router brings back speeds 
• Top and free shows memory levels and cpu usage as being normal
• ALSO, I've noticed that the host validation for ssh login is SERIOUSLY slow when this happens. I know disabling the host validation solves this, but it is correlative with the slow internet speeds I'm experiecning. At fresh boot, the host validation time is pretty fast
• I also notice running tcpdump is noticeably slower after ERL has been running for a few days as opposed to a few hours after a fresh reboot. 

Offload Status:

IP offload module : loaded
IPv4
 forwarding: enabled
 vlan : enabled
 pppoe : disabled
 gre : disabled
IPv6
 forwarding: disabled
 vlan : disabled
 pppoe : disabled

IPSec offload module: loaded

Traffic Analysis :
 export : disabled
 dpi : disabled

Router config:

firewall {
    all-ping enable
    broadcast-ping disable
    group {
        network-group Trusted {
            description Trusted
            network 172.16.0.0/27
            network 10.0.3.0/24
        }
    }
    ipv6-receive-redirects disable
    ipv6-src-route disable
    ip-src-route disable
    log-martians disable
    name WAN_IN {
        default-action drop
        rule 2 {
            action accept
            description "Accept Valid"
            log disable
            protocol all
            state {
                established enable
                related enable
            }
        }
    }
    name WAN_LOCAL {
        default-action drop
        description ""
        enable-default-log
    }
    receive-redirects disable
    send-redirects enable
    source-validation disable
    syn-cookies enable
}
interfaces {
    ethernet eth0 {
        address dhcp
        description "Time Warner Cable"
        duplex auto
        firewall {
            in {
                name WAN_IN
            }
            local {
                name WAN_LOCAL
            }
        }
        speed auto
    }
    ethernet eth1 {
        duplex auto
        speed auto
        vif 10 {
            address 10.0.0.254/24
            description "Management Net"
            mtu 1500
        }
        vif 40 {
            address 10.0.2.254/24
        }
        vif 50 {
            address 10.0.3.254/24
        }
        vif 90 {
            address 172.16.0.30/27
        }
    }
    ethernet eth2 {
        address 10.100.100.1/24
        description DMZ
        duplex auto
        mtu 9000
        speed auto
    }
    loopback lo {
    }
}
service {
    dhcp-server {
        disabled false
        hostfile-update disable
        shared-network-name Home {
            authoritative disable
            subnet 10.0.2.0/24 {
                default-router 10.0.2.254
                dns-server 172.16.0.21
                dns-server 8.8.8.8
                lease 300
                start 10.0.2.100 {
                    stop 10.0.2.254
                }
            }
        }
        shared-network-name Management {
            authoritative disable
            subnet 10.0.0.0/24 {
                default-router 10.0.0.254
                dns-server 172.16.0.21
                dns-server 8.8.8.8
                lease 86400
                start 10.0.0.100 {
                    stop 10.0.0.200
                }
                unifi-controller 172.16.0.29
            }
        }
        shared-network-name Trusted {
            authoritative disable
            subnet 10.0.3.0/24 {
                default-router 10.0.3.99
                dns-server 172.16.0.21
                dns-server 8.8.8.8
                lease 300
                start 10.0.3.100 {
                    stop 10.0.3.253
                }
                unifi-controller 172.16.0.29
            }
        }
        shared-network-name vm_net {
            authoritative disable
            subnet 172.16.0.0/27 {
                default-router 172.16.0.15
                dns-server 172.16.0.21
                dns-server 8.8.8.8
                lease 86400
                start 172.16.0.1 {
                    stop 172.16.0.19
                }
            }
        }
    }
    gui {
        https-port 443
    }
    nat {
        rule 5000 {
            description "WAN NAT"
            log disable
            outbound-interface eth0
            protocol all
            type masquerade
        }
    }
    ssh {
        port 22
        protocol-version v2
    }
}
system {
    domain-search {
    }
    host-name ubnt
    ipv6 {
        disable
        disable-forwarding
    }
    login {
        user admin {
            authentication {
                encrypted-password ****************
                plaintext-password ****************
            }
            level admin
        }
    }
    name-server 8.8.8.8
    ntp {
        server 0.ubnt.pool.ntp.org {
        }
        server 1.ubnt.pool.ntp.org {
        }
        server 2.ubnt.pool.ntp.org {
        }
        server 3.ubnt.pool.ntp.org {
        }
    }
    offload {
        ipv4 {
            forwarding enable
            vlan enable
        }
    }
    syslog {
        global {
            facility all {
                level notice
            }
            facility protocols {
                level debug
            }
        }
    }
    time-zone America/Chicago
    traffic-analysis {
        dpi disable
        export disable
    }
}