Arch Linux and slow Wi-Fi speed/connection. Broadcom BCM4313 - networking

Question

I'm trying to figure out what is the reason of such a slow speed using wi-fi on Arch. I have Windows 8 installed alongside with the Arch and I can say for sure that at Windows the speed is ultimately higher. When I switch back to Arch and start surfing the Internet I feel like my internet speed is clipped half! I use Arch quite recently and many things I don't know (especially networking). So here are the steps of how I usually connect to the internet using wpa_supplicant:
cat wpa.conf
network={
ssid="Home"
#psk="pass"
psk=05a9b845b68a55291d1d5b94e50b9b1811706b0746d89e67f581cc5f7b88b758
}
sudo wpa_supplicant -B -iwlp10s0b1 -cwpa.conf
sudo dhcpcd wlp10s0b1
There are card details:
iwconfig (after connection to internet)
wlp10s0b1 IEEE 802.11bgn ESSID:"Home"
Mode:Managed Frequency:2.412 GHz Access Point: E0:CB:4E:ED:8F:48
Bit Rate=28.9 Mb/s Tx-Power=19 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:off
Link Quality=70/70 Signal level=-39 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:2168 Invalid misc:12 Missed beacon:0
lspci -k
...
0a:00.0 Network controller: Broadcom Corporation BCM4313 802.11bgn Wireless Network Adapter (rev 01)
Subsystem: Hewlett-Packard Company Device 1795
Kernel driver in use: bcma-pci-bridge
Kernel modules: bcma
The output of dmesg:
[ 12.123632] bcma: bus0: Found chip with id 0x4313, rev 0x01 and package 0x08
[ 12.123663] bcma: bus0: Core 0 found: ChipCommon (manuf 0x4BF, id 0x800, rev 0x24, class 0x0)
[ 12.123689] bcma: bus0: Core 1 found: IEEE 802.11 (manuf 0x4BF, id 0x812, rev 0x18, class 0x0)
[ 12.123741] bcma: bus0: Core 2 found: PCIe (manuf 0x4BF, id 0x820, rev 0x11, class 0x0)
[ 12.135277] bcma: bus0: Bus registered
[ 13.610907] b43: probe of bcma0:1 failed with error -524
[ 13.695776] brcmsmac bcma0:1: mfg 4bf core 812 rev 24 class 0 irq 19
[ 13.928846] brcmsmac bcma0:1 wlp10s0b1: renamed from wlan0
[ 104.737832] brcmsmac bcma0:1: brcms_ops_bss_info_changed: qos enabled: false (implement)
[ 104.737847] brcmsmac bcma0:1: brcms_ops_config: change power-save mode: false (implement)
[ 448.818973] brcmsmac bcma0:1: brcmsmac: brcms_ops_bss_info_changed: associated
[ 448.818982] brcmsmac bcma0:1: brcms_ops_bss_info_changed: qos enabled: true (implement)
[ 449.080594] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: txop exceeded phylen 159/256 dur 1778/1504
[ 449.085704] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: txop exceeded phylen 137/256 dur 1602/1504
[ 528.990763] brcmsmac bcma0:1: brcms_ops_bss_info_changed: arp filtering: 1 addresses (implement)
[ 688.637057] brcmsmac bcma0:1: brcms_ops_bss_info_changed: arp filtering: 0 addresses (implement)
[ 698.117592] brcmsmac bcma0:1: brcms_ops_bss_info_changed: arp filtering: 1 addresses (implement)
[ 792.648850] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 792.668819] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 792.825554] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 1114.888310] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 1114.918308] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 1240.631071] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 2282.871425] brcmsmac bcma0:1: START: tid 1 is not agg'able
[ 2282.884764] brcmsmac bcma0:1: START: tid 1 is not agg'able
Some notes in advance, please do not suggest check the router settings (everything is set correctly and tested on different devices), so the problem isn't in the router nor the physical obstacles.