rahmu wroteI don't exclude completely what you said, but I doubt Joomla has anything to do with it. What seems more probable is that there's a problem with the connection between VISP and your web host.
I would compare some traceroutes from several ISPs to 1and1, maybe something would appear here. And not just your website. Try a few others you may know are hosted there as well. Although, ultimately I doubt there's much you can do on your side.
If you ever do decide to launch the investigation, please feel free to share results here.
These are the results of the VISP trace
Tracing route to perfora.net [74.208.88.222]
over a maximum of 30 hops:
1 2 ms 2 ms 6 ms 172.16.1.1
2 21 ms 2 ms 2 ms 172.16.1.1
3 8 ms 2 ms 2 ms rev-154-189.globalproof.net [194.146.154.189]
4 13 ms 80 ms 54 ms 10.48.84.1
5 7 ms 12 ms 13 ms rev-153-8.globalproof.net [194.146.153.8]
6 18 ms 18 ms 4 ms 192.168.11.2
7 36 ms 26 ms 7 ms 192.168.11.1
8 28 ms 22 ms 18 ms 172.16.41.53
9 59 ms 58 ms 65 ms 212.73.241.85
10 59 ms 54 ms * ae-0-11.bar1.Milan1.Level3.net [4.69.142.189]
11 192 ms 190 ms 194 ms ae-7-7.ebr2.Paris1.Level3.net [4.69.142.186]
12 194 ms 194 ms 197 ms ae-91-91.csw4.Paris1.Level3.net [4.69.161.90]
13 192 ms 192 ms 192 ms ae-92-92.ebr2.Paris1.Level3.net [4.69.161.105]
14 224 ms 198 ms 213 ms ae-44-44.ebr2.Washington1.Level3.net [4.69.137.62]
15 199 ms 223 ms 222 ms ae-72-72.csw2.Washington1.Level3.net [4.69.134.150]
16 198 ms 194 ms 197 ms ae-71-71.ebr1.Washington1.Level3.net [4.69.134.133]
17 195 ms 196 ms 202 ms ae-2-2.ebr3.Atlanta2.Level3.net [4.69.132.85]
18 196 ms 194 ms 196 ms ae-7-7.ebr3.Dallas1.Level3.net [4.69.134.21]
19 231 ms 199 ms 200 ms ae-83-83.csw3.Dallas1.Level3.net [4.69.151.157]
20 199 ms 195 ms 211 ms ae-82-82.ebr2.Dallas1.Level3.net [4.69.151.154]
21 204 ms 198 ms * ae-5-5.car1.KansasCity1.Level3.net [4.69.135.229]
22 224 ms 195 ms 196 ms 11-INTERNET.car1.KansasCity1.Level3.net [4.53.32.10]
23 202 ms 200 ms 199 ms ae-10.bb-c.ms.mkc.us.oneandone.net [74.208.1.82]
24 * 199 ms 213 ms ae-10.bb-c.slr.lxa.us.oneandone.net [74.208.6.106]
25 198 ms 195 ms 194 ms ae-2.gw-dista-a.slr.lxa.us.oneandone.net [74.208.1.121]
26 202 ms 197 ms 197 ms vl-987.gw-ps3.slr.lxa.us.oneandone.net [74.208.1.135]
27 222 ms 195 ms 197 ms perfora.net [74.208.88.222]
These are the results of SODETEL
Tracing route to perfora.net [74.208.88.222]
over a maximum of 30 hops:
1 141 ms 29 ms 13 ms 10.180.12.9
2 2 ms 2 ms 3 ms 10.180.12.9
3 9 ms 11 ms 10 ms 89.108.165.161
4 * 11 ms 19 ms 10.255.111.13
5 33 ms 43 ms 34 ms 172.16.1.66
6 18 ms 21 ms 14 ms 172.16.34.245
7 22 ms 16 ms 17 ms 89.108.129.1
8 72 ms 26 ms 17 ms 192.168.32.42
9 25 ms * 28 ms 172.16.40.9
10 55 ms 62 ms 72 ms te0-7-0-1.ccr22.mrs01.atlas.cogentco.com [149.6.154.5]
11 68 ms 76 ms 77 ms te0-0-0-15.mpd22.par01.atlas.cogentco.com [154.54.36.158]
12 105 ms 76 ms 69 ms te0-7-0-27.mag21.par01.atlas.cogentco.com [154.54.74.154]
13 87 ms 73 ms 67 ms prs-b2-link.telia.net [213.248.86.169]
14 70 ms 69 ms 78 ms prs-bb1-link.telia.net [213.155.135.192]
15 148 ms 271 ms 141 ms nyk-bb1-link.telia.net [213.155.135.5]
16 172 ms 169 ms 165 ms chi-bb1-link.telia.net [213.155.136.71]
17 266 ms 190 ms 192 ms kanc-b1-link.telia.net [213.155.130.177]
18 201 ms 209 ms 214 ms 1o1internet-ic-147344-kanc-b1.c.telia.net [80.239.196.110]
19 188 ms 187 ms 187 ms ae-10.bb-d.slr.lxa.us.oneandone.net [74.208.1.65]
20 187 ms 181 ms 196 ms ae-2.gw-dista-a.slr.lxa.us.oneandone.net [74.208.1.121]
21 199 ms 210 ms * vl-987.gw-ps3.slr.lxa.us.oneandone.net [74.208.1.135]
22 220 ms 211 ms 211 ms perfora.net [74.208.88.222]
Trace complete.
Any conclusions ???